ISEE Upper Level Quantitative : Hexagons

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

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Example Questions

Example Question #1 : Hexagons

Which is the greater quantity?

(a) The area of a regular hexagon with sidelength 1

(b) The area of an equilateral triangle with sidelength 2

Possible Answers:

(b) is greater

It is impossible to tell from the information given

(a) is greater

(a) and (b) are equal

Correct answer:

(a) is greater

Explanation:

A regular hexagon with sidelength \(\displaystyle s = 1\) can be seen as a composite of six equilateral triangles, each with sidelength \(\displaystyle s = 1\). Since area is in direct proportion to the square of the sidelength, the area of the equilateral triangle with sidelength \(\displaystyle s = 2\) is equal to that of four of those triangles. This makes the hexagon greater in area, and it makes (a) the greater quantity.

Example Question #2 : Hexagons

Which is the greater quantity?

(a) The perimeter of a regular pentagon with sidelength 1 foot

(b) The perimeter of a regular hexagon with sidelength 10 inches

Possible Answers:

(a) and (b) are equal.

(b) is greater.

It is impossible to tell from the information given.

(a) is greater.

Correct answer:

(a) and (b) are equal.

Explanation:

The sides of a regular polygon are congruent, so in each case, multiply the sidelength by the number of sides to get the perimeter.

(a) Since one foot equals twelve inches, \(\displaystyle 5 \times 12 = 60\) inches.

(b) Multiply: \(\displaystyle 6 \times 10 = 60\) inches

The two polygons have the same perimeter.

Example Question #3 : Hexagons

A hexagon has six angles with measures \(\displaystyle (x-5)^{\circ}, x^{\circ}, (x+5)^{\circ}, (y-10)^{\circ}, y^{\circ}, (y + 10)^{\circ}.\)

Which quantity is greater?

(a) \(\displaystyle x + y\)

(b) 240

Possible Answers:

(a) and (b) are equal

(a) is greater

It is impossible to tell from the information given

(b) is greater

Correct answer:

(a) and (b) are equal

Explanation:

The angles of a hexagon measure a total of \(\displaystyle 180 (6-2) = 720\). From the information, we know that:

\(\displaystyle (x - 5) + x + (x+5) + (y-10) + y + (y+10) = 720\)

\(\displaystyle x+ x + x + y+ y + y - 5+5 -10 +10= 720\)

\(\displaystyle 3x + 3y = 720\)

\(\displaystyle 3 (x + y) = 720\)

\(\displaystyle 3 (x + y) \div 3 = 720 \div 3\)

\(\displaystyle x + y = 240\)

The quantities are equal.

Example Question #1 : Hexagons

A hexagon has six angles with measures \(\displaystyle (x-10)^{\circ}, x^{\circ}, (x+5)^{\circ}, (y-10)^{\circ}, y^{\circ}, (y + 20)^{\circ}.\)

Which quantity is greater?

(a) \(\displaystyle x + y\)

(b) \(\displaystyle 240\)

Possible Answers:

It is impossible to tell from the information given.

(b) is greater.

(a) is greater.

(a) and (b) are equal.

Correct answer:

(b) is greater.

Explanation:

The angles of a hexagon measure a total of \(\displaystyle 180 (6-2) = 720\).  From the information, we know that:

\(\displaystyle (x-10)+x+(x+5)+ (y-10)+ y+ (y + 20)= 720\)

\(\displaystyle x + x + x + y + y + y -10+5 -10 + 20= 720\)

\(\displaystyle 3x + 3y +5= 720\)

\(\displaystyle 3x + 3y +5-5= 720-5\)

\(\displaystyle 3x + 3y = 715\)

\(\displaystyle 3\left ( x + y \right )= 715\)

\(\displaystyle 3\left ( x + y \right ) \div 3= 715\div 3\)

\(\displaystyle x + y = 238 \frac{1}{3} < 240\)

This makes (b) greater.

Example Question #2 : Hexagons

The angles of Hexagon A measure 

\(\displaystyle A ^{\circ }, B ^{\circ }, 150 ^{\circ }, 150 ^{\circ }, 150 ^{\circ }, 150 ^{\circ }\)

The angles of Octagon B measure 

\(\displaystyle C ^{\circ }, D^{\circ }, 150^{\circ },150^{\circ },150^{\circ },150^{\circ },150^{\circ },150^{\circ }\)

Which is the greater quantity?

(A) \(\displaystyle A + B\)

(B) \(\displaystyle C + D\)

Possible Answers:

(A) is greater

(B) is greater

(A) and (B) are equal

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

Correct answer:

(B) is greater

Explanation:

The sum of the measures of a hexagon is \(\displaystyle 180 ^{\circ } \times (6-2)= 720 ^{\circ }\) . Therefore,

\(\displaystyle A + B + 150 + 150 + 150 + 150 = 720\)

\(\displaystyle A + B +600= 720\)

\(\displaystyle A + B = 120\)

 

The sum of the measures of an octagon is \(\displaystyle 180 ^{\circ } \times (8-2)= 1,080 ^{\circ }\). Therefore,

\(\displaystyle C + D + 150 + 150 + 150 + 150+ 150 + 150 = 1,080\)

\(\displaystyle C + D + 900 = 1,080\)

\(\displaystyle C + D = 180\)

 

\(\displaystyle C + D > A + B\), so (B) is greater.

Example Question #4 : Hexagons

The angles of Pentagon A measure \(\displaystyle 110^{\circ }, 110^{\circ }, 110^{\circ }, y^{\circ }, y^{\circ }\)

The angles of Hexagon B measure \(\displaystyle 130^{\circ }, 130^{\circ }, 130^{\circ }, 130^{\circ },z^{\circ }, z^{\circ }\)

Which is the greater quantity?

(A) \(\displaystyle y\)

(B) \(\displaystyle z\)

Possible Answers:

(B) is greater

(A) is greater

(A) and (B) are equal

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

Correct answer:

(A) is greater

Explanation:

The sum of the measures of the angles of a pentagon is \(\displaystyle 180^{\circ } \times (5-2) =540^{\circ }\). Therefore, 

\(\displaystyle y + y + 110 + 110 + 110 = 540\)

\(\displaystyle 2y +330 = 540\)

\(\displaystyle 2y = 210\)

\(\displaystyle y = 105\)

 

The sum of the measures of a hexagon is \(\displaystyle 180^{\circ } \times (6-2) =720 ^{\circ }\) . Therefore,

\(\displaystyle z + z + 130 + 130 + 130 + 130 = 720\)

\(\displaystyle 2z + 520 = 720\)

\(\displaystyle 2z= 200\)

\(\displaystyle z = 100\)

 

\(\displaystyle y> z\), so (A) is greater.

Example Question #93 : Isee Upper Level (Grades 9 12) Quantitative Reasoning

Right_triangle

A regular hexagon has the same perimeter as the above right triangle. What is the length of one side of the hexagon?

Possible Answers:

\(\displaystyle 18 \frac{2}{3} \textrm{ in}\)

The length cannot be determined from the information given.

\(\displaystyle 12 \frac{2}{5}\textrm{ in}\)

\(\displaystyle 22 \frac{2}{5} \textrm{ in}\)

\(\displaystyle 10 \frac{1}{3}\textrm{ in}\)

Correct answer:

\(\displaystyle 18 \frac{2}{3} \textrm{ in}\)

Explanation:

By the Pythagorean Theorem, the hypotenuse of the right triangle is 

\(\displaystyle \sqrt{14^{2}+48^{2}} = \sqrt{196+2,304} = \sqrt{2,500} = 50\) inches, making its perimeter

\(\displaystyle 14 + 48 + 50 =112\) inches.

The regular hexagon, which has six sides of equal length, has the same perimeter, so each side measures

\(\displaystyle 112 \div 6 = 18 \frac{2}{3}\) inches.

Example Question #101 : Isee Upper Level (Grades 9 12) Quantitative Reasoning

Right_triangle

A regular hexagon has the same perimeter as the above right triangle. What is the length of one side of the hexagon?

Possible Answers:

\(\displaystyle 22 \frac{2}{5} \textrm{ in}\)

The length cannot be determined from the information given.

\(\displaystyle 10 \frac{1}{3}\textrm{ in}\)

\(\displaystyle 12 \frac{2}{5}\textrm{ in}\)

\(\displaystyle 18 \frac{2}{3} \textrm{ in}\)

Correct answer:

\(\displaystyle 18 \frac{2}{3} \textrm{ in}\)

Explanation:

By the Pythagorean Theorem, the hypotenuse of the right triangle is 

\(\displaystyle \sqrt{14^{2}+48^{2}} = \sqrt{196+2,304} = \sqrt{2,500} = 50\) inches, making its perimeter

\(\displaystyle 14 + 48 + 50 =112\) inches.

The regular hexagon, which has six sides of equal length, has the same perimeter, so each side measures

\(\displaystyle 112 \div 6 = 18 \frac{2}{3}\) inches.

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