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McGraw Hill Integrated II, 2012 View details

1. Circles and Circumference

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Exercise 17 Page 719

What is the relationship between the radius and diameter of a circle?

3.7cm

Practice makes perfect

We want to find the length of EF, given that DA= 7.4 centimeters. Let's start by recalling the definitions of radius and diameter.

Radius: Distance from the center of the circle to any point on the circumference.
Diameter: Distance from one side of the circle's circumference, through the center of the circle, to the opposite side.

Now let's review the diagram.

We can see in the diagram that DA is a diameter and EF is a radius of the circle. We are also given that the diameter DA = 7.4 centimeters. According to the definitions, the diameter is twice the radius. Therefore, the length of the radius EF is 7.42= 3.7 centimeters.