All ISEE Upper Level Quantitative Resources
Example Questions
Example Question #1 : How To Find The Angle For A Percentage Of A Circle
What is the angle measure of  in the figure above if the sector comprises 37% of the circle?
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It is very easy to compute the angle of a sector if we know what it is as a percentage of the total circle.  To do this, you merely need to multiply  byÂ
Ëš. Â This yieldsÂ
Ëš.Â
Example Question #2 : Sectors
What is the angle measure of  in the figure above if the sector comprises
%Â of the circle?
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It is very easy to compute the angle of a sector if we know what it is as a percentage of the total circle.  To do this, you merely need to multiply  byÂ
Ëš. Â This yieldsÂ
Ëš.Â
Example Question #1 : Sectors
What is the angle measure of  in the figure if the sector comprises
 of the circle?
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Ëš
Ëš
Ëš
Ëš
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It is very easy to compute the angle of a sector if we know what it is as a percentage of the total circle.  To do this, you merely need to multiply  byÂ
Ëš. Â This yieldsÂ
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Example Question #1 : Sectors
Circle A has twice the radius of Circle B. Which is the greater quantity?
(a) The area of a  sector of Circle A
(b) The area of Circle B
(a) and (b) are equal.
It is impossible to tell from the information given.
(b) is greater.
(a) is greater.
(a) and (b) are equal.
Let  be the radius of Circle B. The radius of Circle A is thereforeÂ
.
AÂ Â sector of a circle comprisesÂ
 of the circle. TheÂ
 sector of circle A has areaÂ
, the area of Circle B. The two quantities are equal.
Example Question #3 : Sectors
What is the area, rounded to the nearest hundredth, of the sector shaded in circle O in the diagram above?
To find the area of a sector, you need to find a percentage of the total area of the circle.  You do this by dividing the sector angle by the total number of degrees in a full circle (i.e. ˚).  Thus, for our circle, which has a sector with an angle ofÂ
Ëš, we have a percentage of:
Now, we will multiply this by the total area of the circle. Â Recall that we find such an area according to the equation:
For our problem,
Therefore, our equation is:
Â
Using your calculator, you can determine that this is approximately .
Example Question #1 : How To Find The Area Of A Sector
What is the area, rounded to the nearest hundredth, of the sector shaded in circle O in the diagram above?
To find the area of a sector, you need to find a percentage of the total area of the circle.  You do this by dividing the sector angle by the total number of degrees in a full circle (i.e. ˚).  Thus, for our circle, which has a sector with an angle ofÂ
Ëš, we have a percentage of:
Now, we will multiply this by the total area of the circle.  Recall that we find such an area according to the equation:
For our problem,Â
Therefore, our equation is:
Â
Using your calculator, you can determine that this is approximately .
Example Question #4 : Sectors
Refer to the above figure, Which is the greater quantity?
(a) The area ofÂ
(b) The area of the orange semicircleÂ
(a) is the greater quantity
It is impossible to determine which is greater from the information given
(b) is the greater quantity
(a) and (b) are equal
(a) is the greater quantity
 has two angles of degree measure 45; the third angle must measure 90 degrees, makingÂ
 a right triangle.
For the sake of simplicity, let ; the reasoning is independent of the actual length. The legs of a 45-45-90 triangle are congruent, soÂ
. The area of a right triangle is half the product of its legs, soÂ
Also, if , then the orange semicircle has diameter 1 and radiusÂ
. Its area can be found by substitutingÂ
 in the formula:
 has a greater area than the orange semicircle.
Example Question #5 : Sectors
Refer to the above figure, Which is the greater quantity?
(a) The area of the orange semicircleÂ
(b) The area ofÂ
It is impossible to determine which is greater from the information given
(b) is the greater quantity
(a) and (b) are equal
(a) is the greater quantity
(b) is the greater quantity
 has two angles of degree measure 60; its third angle must also have measure 60, makingÂ
 an equilateral triangleÂ
For the sake of simplicity, let ; the reasoning is independent of the actual length. The area of equilateralÂ
 can be found by substitutingÂ
 in the formula
Also, if , then the orange semicircle has diameter 1 and radiusÂ
. Its area can be found by substitutingÂ
 in the formula:
Â
 has a greater area than the orange semicircle.
Example Question #174 : Plane Geometry
The above circle, which is divided into sectors of equal size, has diameter 20. Give the area of the shaded region.
The radius of a circle is half its diameter; the radius of the circle in the diagram is half of 20, or 10.
To find the area of the circle, set  in the area formula:
The circle is divided into sixteen sectors of equal size, five of which are shaded; the shaded portion is
.
Example Question #1 : How To Find The Length Of An Arc
The clock at the town square has a minute hand eight feet long. How far has its tip traveled since noon if it is now 12:58 PM?
This question is asking for the length of an arc corresponding to  of a circle with radius eight feet. The question can be answered by evaluating forÂ
:
Â
Â
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All ISEE Upper Level Quantitative Resources
