Answer:
F. 75 units
Step-by-step explanation:
Use the pythagorean theorem: [tex]a^2+b^2=c^2[/tex], which a and b are the lengths of the shorter sides, and c is the length of the hypotenuse, the longest side. So in this problem we have [tex]21^2+72^2=c^2\\[/tex]. This can be simplified to 5625=[tex]c^2[/tex]. Taking the square root on both sides we get c is 75.
