WMA12/01 IAL (Edexcel) P2 January 2022 Q7 Trigonometry, Equations & Identities

[@sadiyosharaf1318]

Thank you so much Mr Hassaan may Allaah bless you

[@raidenx_knights1026]

may Allah bless you sir

[@kimaniotieno5794]

Future saver

[@StrangerinGenZ]

What happens if you use quadrants I am confused at this part 8:28

[@gustybot]

is it possible for them to ask us to prove the identities?

[@ahmedbanaga8185]

Hey sir quick question... why did you subtract 1.68 from 2pi instead of subtracting 2pi from 1.68? I'm just wondering because in the other topic paper questions you did the latter. Can you tell me what prompted you to do it this way?

[@MrHassaansMathsChannel]

When finding the main solutions for cosine...you take the calculator answer and subtract from 360... oncee you have found both main solutions then u find the angles which are 360 more or 360 less than them if they are in the range

[@MrHassaansMathsChannel]

Watch this video where I go into some detail about the basics kzbin.info/www/bejne/iIPXd2mtgbSMhZI

[@onkitkumardutta3719]

in 7(ii) what if (1-sin^2) is used in cos^2? Can we solve with that?

[@MrHassaansMathsChannel]

Well there is no cos²@ ....only sin²@ ... we cannot replace cos@ with 1 - sin²@.... it must be squared.

[@antisocialbarbie1587]

Why is 180 not added but subtracted?

[@MrHassaansMathsChannel]

you can add 180 to the main angle, but it takes us outside of the range. Listen to the video from 7:40

[@Yosef-101]

where is 6c

[@MrHassaansMathsChannel]

kzbin.info/aero/PLquyU_6YLv6eIKus58RTHhQ1fa_thp5qa its in the playlist

[@zaahinmohammed3125]

We’ll I did 7 ii using ASTC Cos^-1(2-root5/2) gives me 1.69 , so now I draw the ASTC diagram and as cos is -ve I draw arrows on S and T and I’m getting (pie -1.69) 1.45 and (pie +1.69) 4.83, how am I wrong ?

[@MrHassaansMathsChannel]

The 1.69 is already in the 2nd quadrant and is therefore one of your answers. You are assuming that it is the associated acute angle... it isnt ... it is the angle all the way from the posotive x axis going into the 2nd quadrant where cosine is negative. To use quadrants to find the other angle in the 3rd quadrant you need to find the associated acute angle by finding pi - 1.69 and then adding that to pi.

[@zaahinmohammed3125]

@@MrHassaansMathsChannel thank you sir