All ACT Math Resources
Example Questions
Example Question #3 : How To Find The Ratio Of Diameter And Circumference
Let represent the area of a circle and
represent its circumference. Which of the following equations expresses
in terms of
?
The formula for the area of a circle is , and the formula for circumference is
. If we solve for C in terms of r, we get
.
We can then substitute this value of r into the formula for the area:
Example Question #62 : Circles
A circle has a radius of . What is the ratio of its circumference to its area?
1. Find the circumference:
2. Find the area:
3. Divide the circumference by the area:
Example Question #63 : Circles
How far must a racehorse run in a lap race where the course is a circle with an area of
?
To find the answer, we need to first find the circumference of the circle then mulitply that by 4 because the racehorse is running 4 laps.
We know that the area of the circle is . We can then find the radius.
Because , our diameter is 12.
We can now find the circumference.
Multiply the circumference by 4 (our racehorse is running 4 laps) to find the answer.
All ACT Math Resources
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