help doing these

Question

16.5=3.14 times r squared times 5 over 3

Answer 1

16.5 = pi(r^2)(5/3)

16.5 = 3.14(r^2)(5/3)

16.5)(3/5) = 3.14r^2

3.14r^2 = 3.3(3)

r^2 = 9.9/3.14

r = sqr(9.9/3.14)

r = about 1.776

1.776 = the radius of a circle with area = 9.9