### Home > PC > Chapter 4 > Lesson 4.2.3 > Problem 4-101

4-101.

Find *r* first in terms of *x* using proportions.

Area = π *r*^{2}

Substitute your result for *r* into the area formula.

4-101.

Find *r* first in terms of *x* using proportions.

Area = π *r*^{2}

Substitute your result for *r* into the area formula.