### Home > MC1 > Chapter 9 > Lesson 9.3.2 > Problem 9-138

9-138.

Remember that a circle's area is equal to *πr* ^{2}, where *r* is the radius.

*π*(3)^{2} = *π*(9) = 9*π* ≈ 28.26 sq cm.

The radius is equal to half the diameter. Remember to check your work.