Question 739855
{{{a^2 + b^2 = c^2}}}


{{{L^2 + W^2 = (hypotenuse)^2}}}


{{{x^2 + 12^2 = 20^2}}}


{{{x^2 + 144 = 400}}}


{{{x^2 = 256}}}


{{{x = sqrt(256)}}}


{{{x = 16}}}


So the length is <font color="red">16 cm</font>