ISEE Upper Level Math : Plane Geometry

Study concepts, example questions & explanations for ISEE Upper Level Math

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Example Questions

Example Question #191 : Plane Geometry

Find the area of a circle with a diameter of 16in.

Possible Answers:

Correct answer:

Explanation:

To find the area of a circle, we will use the following formula:

where r is the radius of the circle. 

Now, we know the diameter is 16in. We also know the diameter is two times the radius. Therefore, the radius is 8in. So, we get

Example Question #51 : Circles

A circle has a diameter of 18cm. Find the area.

Possible Answers:

Correct answer:

Explanation:

To find the area of a circle, we will use the following formula:

where r is the radius of the circle. 

 

Now, we know the diameter of the circle is 18cm.  We also know the diameter is two times the radius.  Therefore, the radius is 9cm.

Knowing this, we can substitute into the formula.  We get

Example Question #1 : Circumference Of A Circle

What is the circumference of a circle with a radius equal to ?

Possible Answers:

Correct answer:

Explanation:

The circumference can be solved using the following equation:

Example Question #1 : Circumference Of A Circle

The radius of a circle is . Give the circumference of the circle in terms of .

Possible Answers:

Correct answer:

Explanation:

The circumference can be calculated as , where is the radius of the circle.

Example Question #2 : How To Find Circumference

The area of a circle is . Give the circumference  of the circle in terms of .

Let .

Possible Answers:

Correct answer:

Explanation:

The area of a circle can be calculated as , where   is the radius of the circle. 

The circumference can be calculated as , where is the radius of the circle.

 

 

 

Example Question #2 : Circumference Of A Circle

What is the circumference of a circle with a radius of ?

Possible Answers:

Correct answer:

Explanation:

The circumference can be solved using the following equation:

Where  represents the radius. Therefore, when we substitute our radius in we get:

Example Question #1 : Know And Use The Formulas For The Area And Circumference Of A Circle: Ccss.Math.Content.7.G.B.4

The perimeter of a given rectangle is equal to the circumference of a given circle. The circle has radius  inches; the width of the rectangle is  inches. What is the length of the rectangle?

Possible Answers:

 inches

 inches

 inches

 inches

 inches

Correct answer:

 inches

Explanation:

The circumference of a circle with radius  inches is 

 inches.

The perimeter of the rectangle is therefore  inches. To find its length, substitute  and  into the equation and solve for :

 inches

Example Question #191 : Geometry

Sector

The area of the shaded region in the above diagram is . Give the circumference of the circle.

Possible Answers:

Correct answer:

Explanation:

The shaded region is an  sector; this represents 

 

of the circle. The area of the region is therefore

,

where  is the radius. Setting  and solving for :

The circumference of a circle is its radius multiplied by , or

Example Question #1 : How To Find Circumference

A circle has a radius of 5 miles, what is its circumference?

 

Possible Answers:

Correct answer:

Explanation:

A circle has a radius of 5 miles, what is its circumference?

To find circumference, use the following formula:

Where r is our radius.

Plug in 5 miles to get our answer:

Example Question #2 : How To Find Circumference

While mailing some very important letters, you decide to use your circular rubber stamp. If the stamp has a radius of 3.5 cm, what is the circumference of the stamping surface?

Possible Answers:

Cannot be determined from the information provided.

Correct answer:

Explanation:

While mailing some very important letters, you decide to use your circular rubber stamp. If the stamp has a radius of 3.5 cm, what is the circumference of the stamping surface?

Find circumference via the following:

Where r is our radius, which is 3.5 cm.

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