All Basic Geometry Resources
Example Questions
Example Question #106 : How To Find Circumference
Find the circumference of a circle whose diameter, , is 10.
Note:
The formula for circumference is
.
We were initially given diameter, so to get the radius we divide d by 2.
.
We then solve by saying
Example Question #302 : Circles
The area of a circle is . What is the circumference?
The area of a circle is , so in this case the radius squared is 4. Since the square root of 4 is 2, the radius has length 2. To find the circumference, use the formula . In this case,
Example Question #301 : Circles
The radius of the circle shown here is units long. What is its circumference?
The formula for the circumference of a circle given its radius is . For the circle given in the problem, units, and so
.
Hence, the circumference of this circle is units.
Example Question #301 : Radius
A circle has diameter 20.
True or false: The circumference is greater than 60.
True
False
True
The circumference of a circle is its diameter multiplied by , so, since the diameter is 20, the circumference is . Also,
,
so, multiplying both sides by 20 by the Multiplication Property of Inequality,
and
.
The circumference is indeed greater than 60.
Example Question #301 : Plane Geometry
Ashley has a square room in her apartment that measures 81 square feet. What is the circumference of the largest circular area rug that she can fit in the space?
In order to solve this question, first calculate the length of each side of the room.
The length of each side of the room is also equal to the length of the diameter of the largest circular rug that can fit in the room. Since , the circumference is simply
Example Question #1 : How To Find The Length Of The Diameter
Give the diameter of a circle whose circumference is .
Example Question #1 : How To Find The Length Of The Diameter
The perimeter of a circle is 36 π. What is the diameter of the circle?
3
6
36
18
72
36
The perimeter of a circle = 2 πr = πd
Therefore d = 36
Example Question #302 : Plane Geometry
Two circles have only one point in common. Both circles have radii of . If point is on the first circle and point is on the second circle, what is longest possible distance of line ?
18
20
24
6
12
24
Example Question #1 : How To Find The Length Of The Diameter
What is the name of the segment in green?
Radius
Ray
Diagonal
Chord
Diameter
Diameter
The diameter is the maximum distance between two points on a circle's perimeter. The diameter passes through the circle's center.
Example Question #303 : Plane Geometry
The area of a circle is . What is its diameter?
First solve for the radius:
Note that , where is the radius and is the diameter.
Therefore, .
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