Circles Exercises

Example 1

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

Hint

Look up the formula that relates circumference to radius.

Example 2

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

Hint

Look up the formula that relates circumference to radius.

Example 3

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

Hint

Look up the formula that relates circumference to radius.

Example 4

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

Hint

Look up the formula that relates circumference to radius.

Example 5

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

Hint

Look up the formula that relates arc length to arc measure and radius.

Example 6

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

Hint

Look up the formula that relates arc length to arc measure and radius.

Example 7

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

Hint

Look up the formula that relates arc length to arc measure and radius.

Example 8

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

Hint

Look up the formula that relates arc length to arc measure and radius.

Example 9

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

Hint

Remember that a semicircle is an arc with length 180°.

Example 10

In the figure below, points A, B, and C are on the circle. mABC = 135° and mBC = 103°. What is mAB?

Hint

Time to dust off the Arc Addition Postulate.

Example 11

In the figure below, points W, X, Y, and Z are on the circle. If mWX = 24°, mXY = 67°, and mYZ = 100°, what is mZW?

Hint

All arcs in a circle must add up to 360°, and we're lookin' for the arc of the unmarked part of the circle.

Circles Exercises

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Example 11

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