# Circles

### Example 1

Find the exact circumference of a circle with radius 7 m.

### Example 2

Find the exact circumference of a circle with radius 89 cm.

### Example 3

The circumference of a circle is 25π cm. What is its exact radius?

### Example 4

The circumference of a circle is 185 cm. What is its exact radius?

### Example 5

Find the exact length of an arc with measure 10° and radius 3 km.

### Example 6

Find the length of an arc with measure 137° and radius 18 cm. Round your answer to two decimal places.

### Example 7

Suppose an arc has length 17 m and measure 256°. What must its radius be? Round your answer to two decimal places.

### Example 8

Find the radius of an arc with length 35 km and measure 180°. Round your answer to two decimal places.

### Example 9

What is the exact length of a semicircle with radius 5 km?

### Example 10

In the figure below, points *A*, *B*, and *C* are on the circle. m*ABC* = 135° and m*BC* = 103°. What is m*AB*?

### Example 11

In the figure below, points *W*, *X*, *Y*, and *Z* are on the circle. m*WX* = 24°, m*XY* = 67°, and m*YZ* = 100°. What is m*ZW*?