a circle has an area of 81pi square feet. what is its radius?

Question

a. 9ft

b. 9ft^2

c. 20.5 ft

d. 40.5 ft

Answer 1

Area = pir^2 = 81pi

r^2 =81

r= sqr81= 9 ft

A is correct 9 ft

B would be except it has the wrong units 9 ft^2 is a 2 dimensional unit for area, not for length like the radius