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)##.