Say that a and b are the lengths of the legs of a right triangle and c is the length of the hypotenuse. Find b if a = 21 and c = 29.

A) b = 40

B) B = 20

C) B = 10

D) B = 400

When the triangle is a right triangle, you can use the Pythagorean theorem. The formula would be

c^2 = a^2 + b^2

If a = 21 and c=29, thus

b^2 = c^2 - a^2

b^2 = 29^2 - 21^2

b^2 = 400

b = square root (400)

b = 20 units.

Thus, the answer is D) B = 400