How do you find the hypotenuse of a isosceles right triangle?

##"hypotenuse" = l * sqrt2##

An isosceles right triangle has a ##90^@## angle between its two equal sides, let's say ##l##.

If the hypotenuse is ##"hyp"##, you can use Pythagoras' Theorem to write

##"hyp"^2 = l^2 + l^2##

##"hyp" = sqrt(l^2 + l^2)##

##"hyp" = sqrt(2l^2) = l * sqrt(2)##

So in order to find the hypotenuse of an isosceles right triangle, you need to multiply the length of one of two equal sides by ##sqrt(2)##.