# ISEE Upper Level Quantitative : Pentagons

## Example Questions

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### Example Question #1 : How To Find The Length Of The Side Of A Pentagon

A pentagon with a perimeter of one mile has three congruent sides. The second-longest side is 250 feet longer than any one of those three congruent sides, and the longest side is 500 feet longer than the second-longest side.

Which is the greater quantity?

(a) The length of the longest side of the pentagon

(b) Twice the length of one of the three shortest sides of the pentagon

(a) is greater.

(a) and (b) are equal.

(b) is greater.

It is impossible to tell from the information given.

(b) is greater.

Explanation:

If each of the five congruent sides has measure , then the other two sides have measures  and . Add the sides to get the perimeter, which is equal to  feet, the solve for :

feet

Now we can compare (a) and (b).

(a) The longest side has measure  feet.

(b) The three shortest sides each have length 856 feet; twice this is  feet.

(b) is greater.

### Example Question #1 : Pentagons

A regular pentagon has perimeter one yard. Which is the greater quantity?

(A) The length of one side

(B) 7 inches

(A) and (B) are equal

It is impossible to determine which is greater from the information given

(B) is greater

(A) is greater

(A) is greater

Explanation:

One yard is equal to 36 inches. A regular pentagon has five sides of equal length, so one side of the pentagon has length

inches.

Since , (A) is greater.

### Example Question #1 : Pentagons

The sum of the lengths of three sides of a regular pentagon is one foot. Give the perimeter of the pentagon in inches.

It is impossible to determine the perimeter from the information given.

Explanation:

A regular pentagon has five sides of the same length.

One foot is equal to twelve inches; since the sum of the lengths of three of the congruent sides is twelve inches, each side measures

inches.

The perimeter is

inches.

### Example Question #2 : Pentagons

One side of a regular pentagon is 20% longer than one side of a regular hexagon. Which is the greater quantity?

(A) The perimeter of the pentagon

(B) The perimeter of the hexagon

(A) and (B) are equal

It is impossible to determine which is greater from the information given

(B) is greater

(A) is greater

(A) and (B) are equal

Explanation:

Let  be the length of one side of the hexagon. Then its perimeter is .

Each side of the pentagon is 20% greater than this length, or

.

The perimeter is five times this, or .

The perimeters are the same.

### Example Question #2 : Pentagons

The length of one side of a regular octagon is 60% of that of one side of a regular pentagon. What percent of the perimeter of the pentagon is the perimeter of the octagon?

It is impossible to answer the question from the information given.

Explanation:

Let  be the length of one side of the regular pentagon. Then its perimeter is .

The length of one side of the regular octagon is 60% of , or , so its perimeter is .The answer is therefore the percent  is of , which is

### Example Question #121 : Isee Upper Level (Grades 9 12) Quantitative Reasoning

One side of a regular hexagon is 20% shorter than one side of a regular pentagon. Which is the greater quantity?

(A) The perimeter of the pentagon

(B) The perimeter of the hexagon

(A) and (B) are equal

(B) is greater

(A) is greater

It is impossible to determine which is greater from the information given

(A) is greater

Explanation:

Let  be the length of one side of the pentagon. Then its perimeter is .

Each side of the hexagon is 20% less than this length, or

.

The perimeter is five times this, or .

Since  and  is positive, , so the pentagon has greater perimeter, and (A) is greater.

### Example Question #5 : Pentagons

A pentagon has five angles whose measures are .

Which quantity is greater?

(a)

(b) 180

(a) and (b) are equal

(a) is greater

It is impossible to tell from the information given

(b) is greater

(a) and (b) are equal

Explanation:

The angles of a pentagon measure a total of . From the information, we know that:

making the two quantities equal.

### Example Question #1 : Pentagons

A pentagon has five angles whose measures are .

Which quantity is greater?

(a)

(b)

(b) is greater.

It is impossible to tell from the information given.

(a) is greater.

(a) and (b) are equal.

It is impossible to tell from the information given.

Explanation:

The angles of a pentagon measure a total of . From the information given, we know that:

However, we cannot tell whether  or  is greater. For example, if , then ; if , then

### Example Question #1 : Pentagons

Pentagon  and hexagon  are both regular and have equal sidelengths. Diagonals  and  are constructed.

Which is the greater quantity?

(a)

(b)

(a) and (b) are equal.

It is impossible to tell from the information given.

(a) is greater.

(b) is greater.

(a) is greater.

Explanation:

In both situations, the two adjacent sides and the diagonal form an isosceles triangle.

By the Isosceles Triangle Theorem,   and  . Also, since the measures of the angles of a triangle total , we know that

and

.

We can use these equations to compare  and .

(a)

(b)

### Example Question #2 : Pentagons

Pentagon  and hexagon  are both regular, with their sidelengths equal. Diagonals  and  are constructed.

Which is the greater quantity?

(a)

(b)

It is impossible to tell from the information given.

(a) and (b) are equal.

(a) is greater.

(b) is greater.