What is the radius of a circle that has a circumference of 81 π square inches? A. 9 inches
B. 18 inches
C. 40.5 inches
d. 81 inches

r≈12.89

Step-by-step explanation:

Using the formula

C=2πr

Solving for r

r=C

2π=81

2·π≈12.89155

step-by-step explanation:

x^2 -12x + 36 + y^2 = 36

x^2 + y^2 = 12x

r^2 = 12rcos(theta)

r = 12 cos(theta)

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.