Given 3 triangles - Find the length between AB. How much do you know about TRIANGLES?

[@johnmarchington3146]

John, I feel I should point out that the square root of 289 is EXACTLY 17 (positive value only chosen). 8 - 15 - 17 is the first primitive member of a specific Pythagorean triple family, where the lengths of the two larger sides differ by 2 each time. I've been spending a lot of time looking into these triples and they have some fascinating properties. I accept that the square root is going to be immediately squared again, so it really doesn't matter if it is an integer or not.

[@joejoe8322]

D. As a 67 year old that loved math and used it throughout my career in construction, now retired, I really enjoy your show to help me keep my skills and love of math alive. Keep it up, thanks.

[@mauriziograndi1750]

Sqrt389 = 19.72 I found by inspection without writing anything. I am glad that the brain still working at 77.

[@wr2740]

I skipped a couple steps by using substitution. AB^2 = AC^2 + BC^2. since AC^2 = 8^2 + 15^2 and BC^2 = 8^2 + 6^2, AB^2 = 8^2 +15^2 + 8^2 + 6^2. And then solved from there. You don't need to figure out what AC or BC is, just their squares.

[@pandurangaraonimmagadda9966]

AB=√(289+100)=√389 ,so answer is (d)

[@johnmarchington3146]

The right angle triangle on the right is simply a 3-4-5 triangle doubled up so its hypotenuse is 10. The lower, left triangle is an 8-15-17 triangle, so that leaves AB² = 10² + 17², or 100 + 289, so AB = sq root of 389, which is (d).

[@chrisdissanayake6979]

C) 19.7 ------ According to Pythagorean theorem, 8^2 + 15^2 =289 8^2+ 6^2 = 100 289+100 = 389= AB^2 AB = √389 = ~ 19.2

[@erdemmemisyazici3950]

This was fun. I first guessed it at 19.7 just by visual approximation. Then I thought, what the heck he is putting 8 and 6 on either side of this triangle, might as well work the rest out. As it turns out 19.7 was for the lazy to guesstimate and the problem designer knows it. Close but not quite. Sneaky, I love it.

[@OldJoe212]

That was a fun one, thanks.

[@EricWells-s2p]

The square root of 289 is NOT irrational. It is equal to the integer / whole number 17. Please consider posting a correction to this video.

[@russelllomando8460]

got sr 389 remember the tripilets 3-4-5 and 8-15-17 thanks for the fun

[@Stylux-z1p]

Not much, This one is all about Pythagorean theorem lets name the Triangle with line AB , Right angle Triangle ABC -> angle C = 90° line AB is the hypotenuse of triangle ABC AB² = [√(8² + 15²)]² + [(√8² + 6²)]² AB² = [√(64 + 225)]² + [√(64 + 36)]² AB² = (√289)² + (√100)² AB² = 289 + 100 AB² = 389 AB = √389 ≈ 19.723082923 --> D ✔

[@Hewhowalks-fv5mq]

good question made me have to work it out

[@josephlaura7387]

d

[@richardl6751]

At 9:20 17^2=289 Come on John, you should have known that.

[@raya.pawley3563]

Thank you

[@luillierstephane1463]

D or approximately 19.723 But you did an error John. Sqrt of 289 is not an irrational number, it's simply 17.

[@calvinmasters6159]

6 - 8 - 10 is a Pythag triple 8 - 15 - 17 is a Pythag triple (17)^2 + 100 = AB^2, AB = sqrt(389)

[@imagseer]

I went straight for the decimal answer. Now I see what you mean by exact.

[@adgf1x]

AB=389^0.5 option D is ans

[@charlesmitchell5841]

C) 19.7

[@gruenpunkt]

C and D are the same. And both are correct.

[@gavindeane3670]

C and D are not the same, and only D is correct.

[@spdas5942]

Sqrt389

[@francisdelpuech6415]

C and D as square root of 389 is 19.7

[@gavindeane3670]

√389 isn't 19.7. It's close to 19.7 but it isn't 19.7.

[@gavindeane3670]

Lots of Pythagoras... The 6 and 8 are sides of a 3-4-5 triangle, so the hypotenuse of that small triangle is 10. The hypotenuse of the triangle with the 8 and 15 sides is √(15² + 8²) = √(225 + 64) =√289 So AB² = 10² + (√289)² AB² = 100 + 289 AB² = 389 AB = √389 Answer d.

[@suzanalbright8670]

25

[@DavidRobinson-rj2sp]

Simple Pythagorean progression calculating the value of c.

[@Surreal_Wizard]

I have no idea...what ever to do.. so the answer is probably...nineteen point seventwothreeoheighttwoninetwo!

[@yanalkochaha2247]

the right answer is c= 19.7

[@gavindeane3670]

The right answer is D. C is close to the correct answer, but it's not correct.

[@tomtke7351]

8^2+15^2= 17^2 17^2+10^2 = 389 AB = sqrt(389)