I need help on doing this i don't really know how to do it. can someone help me?
also an explination

Step-by-step explanation:
x is the hypotenuse of the triangle.
to find x:
the sum of the square of the other two sides. ( a^2 + b^2 = x^2)
[tex] {x}^{2} = {21}^{2} + {20}^{2} \\ {x}^{2} = 841 \\ \sqrt{ {x}^{2} } = \sqrt{841} \\ x = 29 \: yd[/tex]