Circle Area Applications

The radius of a circle is decreasing at a constant rate of 0.1 cm/sec.  In terms of the circumference C, what is the rate of change of the area of the circle, in square centimeters per second?

• -(0.2)πC

• -(0.1)C

• (0.1)²C

• (0.1)²C

The radius of a circle is increasing at a constant rate of 0.2 meters per second.  What is the rate of increase in the area of the circle at the instant when the circumference of the circle is 20π meters?

• 0.04π m²/sec

• 0.4π m²/sec

• 4π m²/sec

• 20π m²/sec

What is the area of this circle?

• 8322.13

• 1134.11

• 4536.46

• 1267.09

Jacob is painting a circular picture on his wall.  If the painting has a diameter of 4 ft, how much paint will he need to cover the inside of the circle?  Is this question asking you to find the area, circumference, or neither?

• area

• circumference

• neither

A clock face has a diameter of 10 inches. What is the approximate area of the clock face in square inches?

• 314 in²

• 31.4 in²

• 7.85 in²

• 78.5 in²

find the area of the circle with radius 3 cm below.

• 100 cm²

• 225 cm²

• 9 cm²

• 28.26 cm²

Find the area of the circle

• 43.96

• 153.86

• 87.82

• 307.72

What is/are the formula(s) to find the area of a circle?

• πr²

• 2πr

• √π

What is the area of this circle?

• 6082.12

• 1520.53

• 1893.14

• 1292.92

What is the area of this circle?

• 50.27

• 78.23

• 98.12

• 201.06