Answer:
29
Step-by-step explanation:
In a triangle, a^2 + b^2 = c^2 where a and b are the legs and c is the hypotenuse
Given this formula, we knoe c^2 is the product of 21^2 + 20^2.
This gives you 841. Now you just find the square root of 841 which is 29.
Hope this helps :)
