Similar triangle example problems | Similarity | Geometry | Khan Academy

Multiple examples looking for similarity of triangles

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[kylethorburn]

5:00
I've always been taught that if you see a square at the base of a triangle, you know that it's perpendicular.

[JalebJay]

@sgdstb494 You can put everything underneath the square roots by squaring what is outside and multiplying what is in the inside so 9 sqrt 3 = sqrt 27, 27 = sqrt 729, 18 sqrt 3 = sqrt 972. It's fact that anything underneath the square root is to the 1/2 power. (He also probably had the estimates figured out too)

[euchale]

Question: How does one figure out that 27 is smaller than 18 sqrt3?

[sgdstb]

@PoketoMtg don't you mean 9 sqrt 3 = sqrt 243? If so, thanks! I get it now.

[samanthaclark]

for the last pair of triangles why don't you just use the Pythagorean theorem

[sgdstb]

Uhm, I may have a very basic question, I feel stupid to even ask: How do you know that 9 sqrt 3 is less than 27 and 18 sqrt 3 is greater than 27. Did you compute it before hand or is there some rule there that I'm not familiar with?

[HeavenestStCyr]

6:58 to 7:23 is confusing... how'd he get that

[ImJustSayin]

lol what program does he use to draw this stuff. also are you using a stylus? cuz ur writing is good

[yoselinnicole]

I don’t understand anything he saying lmfaooo ima fail geometry I don’t even know what corresponding is