All GED Math Resources
Example Questions
Example Question #1131 : Ged Math
Use 3.14 for pi and round your answer to the nearest hundredth.
Find the area of a circle with a diameter of 12cm.
First we need to recall that the formula for area of a circle is
Where is radius and is 3.14
The circe we are working with has a diameter of 12. The diameter is twice the length of the radius, so to find the radius we cut it in half, and we get 6cm.
Now we can plug our radius and pi into our equation and solve for the area
Following order of operations, first we need to address the exponent. Any number to the second power (squared) is that number times itself one time (in this case it is 6x6)
Next we multiply
Since we multiplied two terms whose units are in cm, our answer is in centimeters squared.
Example Question #161 : Circles
Find the area of a circle given that the distance from its center to its edge is 6.25 meters.
Find the area of a circle given that the distance from its center to its edge is 6.25 meters.
Area of a circle is given by:
We know that our radius is 6.25 m, given that this is the distance from the center to the edge.
Plug in and solve.
So our answer is
Example Question #162 : Circles
If a circle has a radius of 5, what is its area?
Recall the formula for the area of a circle
Here, r is the radius, which in this case is 5
Example Question #169 : Geometry And Graphs
If the diameter of a circle is centimeters long, what is the area of the circle?
(Leave answers in )
The formula to calculate the area of a circle is defined as:
The diameter is twice the length of the radius, or . To find the radius, we must divide the diameter by 2.
Now, we plug in into the formula to find the area of the circle:
Example Question #1 : Central Angles And Arcs
Note: Figure NOT drawn to scale.
Refer to the above diagram.
The length of arc is .
The length of arc is .
What is the area of the white sector?
The circumference of the circle is the sum of the lengths of the arcs, which is
.
The white sector has degree measure
.
The radius of the circle can be found using the circumference formula, setting :
The area of the white sector is therefore
.
Example Question #2 : Central Angles And Arcs
Note: Figure NOT drawn to scale.
Refer to the above diagram.
The area of the shaded sector is . The area of the white sector is .
What is the length of arc ?
The area of the circle is the sum of the areas of the sectors, which is
.
The degree measure of the arc of the shaded sector is
.
The radius can be found by solving for and substituting in the area formula:
The length of arc is
.
Example Question #3 : Central Angles And Arcs
What percent of the above circle has not been shaded in?
There are a total of 360 degrees to a complete circle. The shaded sector has degree measure , so the unshaded sector has degree measure
Also, a sector of is of the circle, so, setting , we find that the unshaded sector is
of the circle. This reduces to
,
the correct percentage.
Example Question #2 : Central Angles And Arcs
What percent of the above circle has been shaded?
There are a total of in a circle. The unshaded portion of the circle represents a sector, so the shaded portion represents a sector of measure
.
This sector represents
of the circle.
Example Question #2 : Central Angles And Arcs
What percentage of a circle is covered by a sector with a central angle of ?
Not enough information to determine.
What percentage of a circle is covered by a sector with a central angle of ?
To find the percentage of a circle from the central angle, we need to use the following formula:
Where theta is our central angle.
Plug in our given degree measurement and simplify.
So, our answer is 66.67%
Example Question #3 : Central Angles And Arcs
Find the length of the minor arc if the circle has a circumference of .
Recall that the length of an arc is a proportion of the circumference, just like how the measure of a central angle is a proportion of the total number of degrees in a circle.
Thus, we can write the following equation to solve for arc length.
Plug in the given central angle and circumference to find the length of the minor arc .