Distinguishing Between the Area and Circumference of a Circle



In this lesson, we distinguish between the area and circumference of a circle using real world problems.

Rhea wants to make a round photo frame for her sister. The radius of the photo frame is 10.2 cm. What is the circumference of photo frame?

Solution

Step 1:

Given radius r = 10.2 cm

Step 2:

Circumference of Photo frame = 2πr = 2(3.14)10.2 = 64.06 cm

Eva makes a round pizza. If the cake is 6.4 inches in radius, how many square inches of cheese layer does she need to put on the pizza?

Solution

Step 1:

Given radius r = 6.4 in

Step 2:

Area of Cheese layer = πr2 = (3.14)(6.4)(6.4) = 128.61 square inches



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