For proof 11, why is a squared equal to (c - b)(c + b) ? I would understand the proof if I could get that one part.

Pythagorean Theorem and its many proofs

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- May 18th 2010, 05:03 PMLord DarkinPythagorean Theorem Proof Question
For proof 11, why is a squared equal to (c - b)(c + b) ? I would understand the proof if I could get that one part.

Pythagorean Theorem and its many proofs - May 18th 2010, 05:10 PMsa-ri-ga-ma
- May 18th 2010, 05:20 PMskeeter
looking at triangle triangle GFH , length "a" is the altitude to the hypotenuse.

using similar triangles GFH, GKF, and FKH, the following ratio between corresponding sides can be made ...

$\displaystyle \frac{c+b}{a} = \frac{a}{c-b}$

cross-multiply and you're there. - May 18th 2010, 06:12 PMLord Darkin
Thanks.

I got it now. (Rofl)