Question

In the right triangle, AC = BC = 2. What is AB?

Answer 1

Use the Pyth. Thm.:  x^2 = 2^2 + 2^2 = 8, so x = +sqrt(8) = +2sqrt(2) (ans.)

Answer 2

Formula for hypotenuse:
$\sqrt{ a^{2} + b^{2} } =c$

a would be AC 
b would be CB
c is AB

$\sqrt{2^2+2^2}$
$\sqrt{4+4}$
$\sqrt{8}$

It is $\sqrt{8}$ or $2 \sqrt{2}$ or about 2.83