Verifying Trigonometric Identities Involving Sum & Difference

[@blissunison1638]

I must say your videos have opened my scope of understanding of calculus and trigonometry as a prospective mathematics teacher. Thanks alot

[@profrobbob]

You're welcome...glad to hear that you found some inspiration! I've been teaching for 21 years and still feel passionate about teaching...when you love what you do and enjoy your surroundings and coworkers, it never really feels like work:) Please sub and share and continue to be inspired to be a teacher...the "future" needs us...BAM!!!

[@profrobbob]

THANK YOU...thank you very much loyal KZbin student! That's the first time anyone has clapped after one of my lessons...thanks for putting a smile on my face:)

[@profrobbob]

And I'm happy to take the credit for that proof:)...but you were the one who sought out extra help and found my video! And now that you've subscribed...together, we will make that perfect learning team. THANKS

[@profrobbob]

:):):) Yeah. Thank you for watching and the very kind words.

[@profrobbob]

AWESOME! Thanks for watching. I hope you do great in you class! Please spread the word:)

[@williamcage7990]

Have to say, I got through PreCal in college (with an A) through self discipline and your teaching. My professor was awful and I greatly appreciate your videos and the time you take to do them. Taking Trig now (with a great teacher) but i still use your videos for great reinforcement of the material. Thanks a million

[@profrobbob]

+William Cage you're welcome and thanks for taking the time to share your appreciation and the continued support of my channel! I hope you have been sharing my channel along the way and please remind everyone how important it is to like, subscribe, support the ads, share thru social medias and with others to support these free educational channels so they can remain free for everyone:D

[@Erin-bc8ic]

I thought Trig was a prerequisite for taking PreCalculus? I was thinking of skipping PreCal and just review it during the break.

[@profrobbob]

You want to watch the 13th video in my trigonometry playlist...Trigonometric Functions of Any Angle. I am so glad you are finding my videos so helpful. Thank you so much for watching, your support, and the hard work you are putting into your studies. I had a retired college professor recently that my proof notation is not exactly correct because I don't seperate my proof from the identity I am verifying...because it unintentionally shows I am assuming to be true what I am trying to proving.

[@profrobbob]

I can never hear those words too often! Thanks for supporting my channel...and be sure to share with your friends:)

[@profrobbob]

I don't remember ever saying there would be no ads. I don't let tobacco and alcohol ads run or ads about gambling...etc. I do not get paid to make these video nor do I charge for them, so the ads are the only monetary support I receive. I hope you are doing great in your trig class and I can continue to be helpful in a couple more of your math classes. Thanks for the great feedback:)

[@profrobbob]

And I too am happy to be your long distance video math teacher in the Philippines all the way from Florida!...together, let's MAKE MATH FUN!

[@herpderpmapleserp149]

Wow my teacher is unfortunately not very good at teaching us this material. She gets frustrated when we all don't know what she's doing and she goes way too fast but everyday after a lesson at school I come home and I know who I will be coming to for help whenever I need it! Thanks!! BAM!

[@profrobbob]

You're welcome...and THANKS for supporting by subscribing! By the time you read this I hope you passed that Trig final with your new found confidence:)

[@stevenoverton8316]

I studied trig but it gave me an identity crisis. These videos have proven therapeutic, curative even, thank you for making them. Looking forward to Fourier series.

[@profrobbob]

Soooo sorry but you will not be seeing it here either:( It's beyond what I teach in high school and who knows what this year will bring between split classes and staying healthy:)

[@stevenoverton8316]

@@profrobbob That's OK.

[@darolaho9318]

You might hear this a lot but Jesus you are saving my grade and actually even making trig somewhat interesting. My current trig professor is kinda meh (to put it lightly) everything is great while he is in class teaching but he skips so many steps when he writes notes so looking back at the notes is almost impossible and his notes online explain literally nothing. But you single handily have made everything easier

[@profrobbob]

Glad to hear that these lessons are so helpful for you and thanks for the sub too! Sounds like a perfect time to share my channel information with your professor as an additional study reference for ALL current and future students who are self-motivated like you and use outside help to continue your studies...BAM!!!

[@smileysteelflex]

thanks for this material man your the best im 28 taking trig for the first time and this is helping a bunch

[@profrobbob]

You're welcome...nice to hear it's helping and welcome back to class! Please take the time to like, subscribe and share this free resource with everyone you can to help us keep growing and remain free:D

[@markdanielgacosta9748]

One of the best video tutorial that I've ever watched. Keep teaching us and uploading ur videos. Thank You Sir RobRob.

[@profrobbob]

+Mark Daniel Gacosta you're welcome...please like, sub and share them with others:D

[@markdanielgacosta9748]

Of course Sir ;)

[@jsx0328]

You are the best teacher ever. Hands down.

[@profrobbob]

Joseph Sauerland and you are one of my best KZbin students ever...BAM!!!

[@OmegaPie69]

Thank you so much. When my professor teaches this in class, I feel she just makes us try to memorize all the "tricks" and not understand it. You have great teaching and I understand everything when you explain it, thank you for the help and for the many videos :)

[@profrobbob]

OmegaPie69 you are so welcome! And thanks you for the compliment and for watching, learning and subbing to my channel. Sounds like you should share your new understanding and my channel with the rest of the class and the teacher as an "additional" study reference...I don't know any teacher who wouldn't like their students to have more resources to study from!:)

[@profrobbob]

Thanks...I try to do a little decorating during the holidays. (obviously it was december when I did this video)...thanks for supporting my channel:)

[@alexanderharris7294]

this is just what i needed to help study for my trig final tomorrow morning, i was stuck on this topic and couldn't quite figure it out thanks

[@meischoice]

This video really helped me understand the identity a lot better! Thank you! I also like your enthusiasm! It is so delightful!

[@butterbrain253]

You are a great teacher. Thank you so much. I could not have gotten through Trig without you. Thanks again

[@profrobbob]

This sounds like goodbye:( Thanks for choosing my channel to learn from and subscribe to! I always like to hear those positive success stories and appreciate the time you watched and supported.

[@plsaty9914]

The way you teach it is all explained very well and steps are not skipped thanks for the time you take to make these videos

[@profrobbob]

+Preston Smith you're welcome and thank you for subbing and recommending my channel to others!

[@georgesadler7830]

Professor RobBob, thank you for another incredible video/lecture on Verifying Trigonometric Identities Involving Sum and Difference in Trigonometry.

[@dil6969]

You are a top-notch teacher! Thanks so much for taking the time to make and share these videos. People like you and Salman Khan make the world a better place.

[@dil6969]

Khan Academy. That's Khan's full name.

[@kallmekrissarchivetiktoks8012]

+Dylan Lewis oh..... I see

[@josiemoreno2404]

Thank you so much taking the time to create these videos. Not only are they fun to watch but extremely helpful when I have a professor that only teaches from the books. I will be watching the rest of your videos to reinforce my math and also pass along the word of your videos. THANK YOU SO MUCH ; ) !!!!

[@profrobbob]

+Josie Moreno you're welcome and THANK YOU SO MUCH for taking the time to study and share my channel with others...that's how we keep growing and helping others. Thanks for sharing your experience and appreciation and keep up those great study habits...sounds like you are on the path to success!

[@Psycyclist]

Thanks for the big help! Thanks to your videos I am able to finish my hw, and feel accomplished since I actually know what I'm doing. I even look forward to test days ;D. Keep on rockin' !

[@elderbonsai]

You are the best math teacher that I have ever had! Thanks so much for your videos. Thanks to you I have an A+ in college trig. :)

[@profrobbob]

THAT'S AWESOME elderbonsai you're welcome and thanks for watching and learning from #ProfRobBob ! You can help me by liking, SUBSCRIBING, supporting the ads and telling all your friends, classmates and teachers to watch and do the same...BAM!!!

[@zyrpentq1395]

how i wish our teacher can teach the same way you do. i really understand it really well. thanks

[@profrobbob]

+YOUNG BLOOD you're welcome! ...you found me so now I can at least be your KZbin teacher:) Thanks again for taking the time to study.

[@profrobbob]

I am sorry. Right now I'm working on videos for a Geometry class I am teaching. I hope you find the help you need.

[@erikhristev3013]

I'm having so much fun right now, gunna ace this math exam

[@profrobbob]

Thanks for watching...don't forget to sub, share and then pass that exam like BAM!!!

[@journiedempster2675]

I absolutely love your videos! My professor is foreign so it is harder to comprehend the way he explains things. I literally come home everyday after class and watch a video corresponding to the work we did in class that day. You're basically the reason I am making it through this class! There are a few problems I don't exactly understand. Ex. Find the values of the trigonometric functions of theta, if sin theta=3/8 and theta is in quadrant II. Any videos on these? Or could you make one? THX!

[@xxkassixo1]

OH MY GOD you are saving my grades this semester. Much appreciated!!!

[@profrobbob]

Teamwork, together, WE are saving your grade...thanks for choosing my channel to learn from and subscribe to Kassi, keep up the extra study time, those "A's" look great on your report card!

[@profrobbob]

If you change the addition to negative between the tan functions, you will no longer be able to get the two sides to match.

[@jasonwilson7020]

First of all, I can not tell you how much I appreciate your videos. You have the best explanations I have seen so far. And your videos are very entertaining. The question is at around 11:42 in the video, you brought down the 1 that was in the top function...never mind the question.....the light just came on haha BAM. NEWAY THX

[@profrobbob]

Thank you for watching and learning from my channel:) One of the best parts of teaching is getting to see the expression chance on a students face when they have one of those "ahh ha" moments.

[@awesomesty]

Thank you so much, seriously! You make everything so easy and fun.

[@profrobbob]

It doesn't, cosAcosB-sinAsinB equals cos(a+b)

[@chordsequencer001]

Hi, I noticed you proved the tan(alpha) + tan(beta) identity from the right-side. So I was wondering if I'm correct proving from the left-side until matched with the right??

[@plsaty9914]

All of these videos help alot!!!!! would, and will recommend!

[@justhinesala5697]

so helpfullll!!! thanks sooo muchhh! you really are blessed with a talent of teaching! :)

[@TheMATHdumb]

um sir in example 3(which is: sin(x+y)/cosxcosy=tanx+tany. what if the tan term is subtraction how will you able to verify it. thanks and sorry for the trouble.

[@inadaizz]

The annotated error at the start is hopelessly confusing for me. Please consider redoing this video. With how popular your channel is I hope you will think its worthwhile.

[@profrobbob]

If you teacher is happy with your proofs as I have them written on the board, you can just ignore the annotation. Some professor did not like the fact that I did not pull sin(x+3pi/2) off to the side separate from the given equation and show that it is equal to -cos(x)

[@jodiwallace9430]

Do you have a website or blog or anything where we could ask you questions?

[@profrobbob]

I answer some questions here, but since I teach full time at my local high school I don't run a blog for Q/A sessions. I unfortunately don't have enough hours in the day:(

[@1996kamalo]

I clapped, I really did. Thank you so much!

[@SK-kn9pl]

thank you so much for sharing this. This really helped, keep up the great work

[@profrobbob]

I will...thanks for subbing and please keep sharing:D

[@coreycrick3057]

Do you have a video for half angle double angle sum to product and product to sum formulas?

[@profrobbob]

At this time I do not...sorry.

[@famosfeldmann8552]

This totally saved my life, ill be back for calculus! subed.

[@profrobbob]

THANK YOU for watching, liking, subscribing and supporting my channel! I'll look forward to helping you with Calculus since I managed to save you for one more semester…lol:)

[@Hygoplayer90]

Hello sir,can you please do a video on Addition and Subtraction trig. functions? PLEASE HELP ME!

[@khairobashiir9207]

is difficult for me

[@profrobbob]

Thank you:)

[@profrobbob]

LOL:D...Just when I think I've heard all the good comments...BAM! There's another one! (good one about the hair, I may use that in class:) Glad I could be of help, although I hear the bald look is in now:)

[@leavethematrix9939]

Is (SinxCosz + CoszSinx) the same as (SinxCosz +SinxCosz)? In other words, does it matter what order the terms are in?

[@profrobbob]

Leave the Matrix Yes they are the same because multiplication is commutative:D

[@nossonweissman]

thanks for your videos!! :)) Looking at this video, isn't cos(-1)=cos1?

[@profrobbob]

That is the cos(x) times -1, not cos(-1). Thank you for watching!!!

[@20yrsofgreatness]

Is there an example of verifying Identities with a tangent or a cotangent in the denominator? I can't get the arithmetic right and they're killing my grade!

[@profrobbob]

I don't remember doing an example like that…sorry. I will say if you have fractions in the denominator you want to combine them into 1 fraction before flipping the denominator up and multiplying by the reciprocal. My full time job is keeping me too busy at the moment to work individual KZbin problems…sorry:(

[@TheMATHdumb]

okay thank you so much sir and nice vid.

[@mohammadsalem9553]

thank you this helped me very much.:):)

[@dogeeatsveggies]

GOD GAVE ME YOU...TO SHOW ME WHATS MATH :D hahahahha... sir i am so happy you are my math teacher :D

[@999saleh999]

BAM !! you're the best

[@leaf8554]

Thank you so much for these videos, my trig teacher gets mad when we ask questions

[@profrobbob]

+Campbell Kane thanks for seeking outside help:)

[@iqrasardar2952]

ProfRobBob

[@tharkrish]

how come CosAcosB equals cos(a+b )

[@tenton2000k]

I am scared to share your videos since a lot of math classes at my college are graded on a tight curve.

[@Afrotastic540]

+tenton2000k lmao

[@profrobbob]

+tenton2000k I would say you are safe if the curve is just adjusted by the top grade in the class. Now if the class is graded on a Normal curve that would just not be nice... guaranteeing that most of the class gets C's, some will fail, and just a few earn A's:O

[@alexbombbird353]

this is college level math?

[@ydowefight4islam]

that duster has been well dusted it seems

[@YAHOOOOOO5]

The best! BAM!

[@profrobbob]

+YAHOO THANKS!!! ...and thanks for liking and subbing, don't forget to tell all your friends to watch and do the same:D

[@profrobbob]

@999saleh999 :):):)

[@16handsoffunfunfun]

i understand it wtf

[@ryanmacintyre5425]

The ad about thattutorguy.com is annoying I'll admit, but mostly because he's a scam artist and isn't anywhere near as helpful as Mr. Tarrou! If you're using Chrome there's a great plugin available that allows you to skip ads so you can get back to the more important things in life, like learning identities so you can pass your trig test!

[@profrobbob]

Hi Ryan. Thanks for the compliment. You help to keep me motivate and I hope you ACE that test on trig identities like BAM!!! While I agree about the annoyance of seeing the Tutor Guy ads on my videos, I allow ads because they are the only revenue I receive for making my videos…and the occasional donation.