GED Math : Radius and Diameter

Example Questions

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Example Question #1 : Radius And Diameter

What is the diameter of a circle with radius of 10 inches?     Explanation:

The diameter is twice the radius:  Example Question #1 : Geometry And Graphs

What is the radius of a circle that has a circumference of ?

20

4

18

12

18

Explanation:

The equation for circumference of a circle is as follows: Plug in the given values and solve for the radius: Now we divide each side by : Example Question #1 : Radius And Diameter

Find the diameter of a circle that has a circumference of ?

20

25

12.5

10

25

Explanation:

We know the equation for the circumference of a circle is . We also know that the the diameter is the twice the radius, so we can write .

Plug in the given values and solve:  Example Question #4 : Radius And Diameter

What is the diameter of a circle with a radius of 9?

20

6

18

16

18

Explanation:

The diameter of a circle is twice the radius:   Example Question #1 : Geometry And Graphs

What is the radius of a circle given the diameter is 22?

6

15

9

11

11

Explanation:

The radius is half of the diameter, or 11.

Example Question #6 : Radius And Diameter

What is the diameter of a circle with an area of ?      Explanation:

In order to solve this question, start by finding the radius.  Recall that the area of a circle is computed as: For our data, this is: Solving for , we get: or Now, recall that the diameter is double the radius.  Thus, it is .

Example Question #1 : Geometry And Graphs

What is the radius of a circle with a circumference of ?    Cannot be computed from the information provided Explanation:

Recall that the circumference formula is: Now, for your data, this gives you: You need to be careful, for some students get confused when they have to divide by .  However, just treat it like any other number or variable.  This means that you can solve for and get: Example Question #8 : Radius And Diameter

What is the diameter of a circle given the area of 30?      Explanation:

Write the area formula of a circle. Substitute the area. Divide by pi on both sides.  Square root both sides.  The radius is: The diameter is double the radius.

The answer is: Example Question #9 : Radius And Diameter

What is the diameter of a circle if the area is ?      Explanation:

Write the formula for the area of a circle. Substitute the area into the equation. Divide by pi on both sides.   The diameter is twice the radius.

The answer is: Example Question #2 : Geometry And Graphs

If the diameter of a circle is 12 feet, what is the radius in yards?      Explanation:

There are three feet in one yard.

Using dimensional analysis, we can determine the given diameter in yards first. The radius is half the diameter.

The answer is: ← Previous 1 3 4 