All ISEE Upper Level Math Resources
Example Questions
Example Question #1 : How To Find The Angle For A Percentage Of A Circle
If sector AJL covers 45% of circle J, what is the measure of sector AJL's central angle?
If sector AJL covers 45% of circle J, what is the measure of sector AJL's central angle?
To find an angle measure from a percentage, simply convert the percentage to a decimal and then multiply it by 360 degrees.
So, our answer is 162 degrees.
Example Question #1 : How To Find The Area Of A Sector
Give the area of the white region of the above circle if has length .
If we let be the circumference of the circle, then the length of is of the circumference, so
The radius is the circumference divided by :
Use the formula to find the area of the entire circle:
The area of the white region is of that of the circle, or
Example Question #211 : Geometry
The circumference of the above circle is . Give the area of the shaded region.
The radius of a circle is found by dividing the circumference by :
The area of the entire circle can be found by substituting for in the formula:
.
The area of the shaded sector is of the total area:
Example Question #211 : Plane Geometry
While visiting a history museum, you see a radar display which consists of a circular screen with a highlighted wedge with an angle of . If the screen has a radius of 4 inches, what is the area of the highlighted wedge?
While visiting a history museum, you see a radar display which consists of a circular screen with a highlighted wedge with an angle of . If the screen has a radius of 4 inches, what is the area of the highlighted wedge?
To begin, let's recall our formula for area of a sector.
Now, we have theta and r, so we just need to plug them in and simplify!
So our answer is
Example Question #1 : Sectors
A giant clock has a minute hand six feet long. How far, in inches, did the tip move between noon and 1:20 PM?
The distance that the tip of the minute hand moves during one hour is the circumference of a circle with radius 6 feet. This circumference is feet. One hour and twenty minutes is hours, so the tip of the hand moved feet, or inches.
Example Question #2 : Sectors
A giant clock has a minute hand three feet long. How far, in inches, did the tip move between noon and 12:20 PM?
It is impossible to tell from the information given
The distance that the tip of the minute hand moves during one hour is the circumference of a circle with radius feet. This circumference is feet. minutes is one-third of an hour, so the tip of the minute hand moves feet, or inches.
Example Question #3 : How To Find The Length Of An Arc
In the above figure, express in terms of .
The measure of an arc - - intercepted by an inscribed angle - - is twice the measure of that angle, so
Example Question #213 : Geometry
In the above diagram, radius .
Give the length of .
The circumference of a circle is multiplied by its radius , so
.
, being an inscribed angle of the circle, intercepts an arc with twice its measure:
The length of is the circumference multiplied by :
.
Example Question #2 : How To Find The Length Of An Arc
While visiting a history museum, you see a radar display which consists of a circular screen with a highlighted wedge with an angle of . If the screen has a radius of 4 inches, what is the length of the arc of the highlighted wedge?
While visiting a history museum, you see a radar display which consists of a circular screen with a highlighted wedge with an angle of . If the screen has a radius of 4 inches, what is the length of the arc of the highlighted wedge?
To begin, let's recall our formula for length of an arc.
Now, just plug in and simplify
So, our answer is 4.54in
Example Question #1 : How To Find The Angle Of A Sector
A giant clock has a minute hand four feet long. Since noon, the tip of the minute hand has traveled feet. What time is it now?
The circumference of the path traveled by the tip of the minute hand over the course of one hour is:
feet.
Since the tip of the minute hand has traveled feet since noon, the minute hand has made
revolutions. Therefore, hours have elapsed since noon, making the time 1:15 PM.
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