SSAT Upper Level Math : Geometry

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

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Example Questions

Example Question #221 : Geometry

Triangle

Refer to the above diagram. 

\displaystyle 45^{\circ } \leq m \angle 1 \leq 50^{\circ }

\displaystyle 130^{\circ } \leq m \angle 3 \leq 140 ^{\circ }

Which of the following could be a measure of \displaystyle \angle 2 ?

Possible Answers:

\displaystyle 80 ^{\circ }

All of the other responses are correct.

\displaystyle 85 ^{\circ }

\displaystyle 95 ^{\circ }

\displaystyle 90 ^{\circ }

Correct answer:

All of the other responses are correct.

Explanation:

The measure of an exterior angle of a triangle is the sum of the measures of its remote interior angles, so 

\displaystyle \angle 3 = \angle 1 + \angle 2

or 

\displaystyle \angle 2 = \angle 3 - \angle 1

Therefore, the maximum value of \displaystyle \angle 2 is the least possible value of \displaystyle \angle 1 subtracted from the greatest possible value of \displaystyle \angle 3:

\displaystyle 140^{\circ } - 45^{\circ } = 95 ^{\circ }

The minimum value of \displaystyle \angle 2 is the greatest possible value of \displaystyle \angle 1 subtracted from the least possible value of \displaystyle \angle 3:

\displaystyle 130^{\circ } - 50^{\circ } = 80 ^{\circ }

Therefore, 

\displaystyle 80^{\circ } \leq \angle 2 \leq 95^{\circ }

Since all of the choices fall in this range, all are possible measures of \displaystyle \angle 2.

Example Question #775 : Ssat Upper Level Quantitative (Math)

Find the angle measurement of \displaystyle y.

 

Picture1

Possible Answers:

\displaystyle 112

\displaystyle 78

\displaystyle 102

\displaystyle 92

Correct answer:

\displaystyle 102

Explanation:

All the angles in a triangle must add up to \displaystyle 180.

\displaystyle 32+46+y=180

\displaystyle 78+y=180

\displaystyle y=102

Example Question #4 : How To Find An Angle In An Acute / Obtuse Triangle

Find the angle measurement of \displaystyle a.

 

 

Picture2

Possible Answers:

\displaystyle 110

\displaystyle 100

\displaystyle 120

\displaystyle 70

Correct answer:

\displaystyle 110

Explanation:

All the angles in a triangle must add up to \displaystyle 180.

\displaystyle a+35+35=180

\displaystyle a+70=180

\displaystyle a=110

Example Question #7 : How To Find An Angle In An Acute / Obtuse Triangle

Find the angle measurement of \displaystyle b.

 

 

Picture3

Possible Answers:

\displaystyle 115

\displaystyle 95

\displaystyle 65

\displaystyle 105

Correct answer:

\displaystyle 115

Explanation:

All the angles in a triangle must add up to \displaystyle 180.

\displaystyle b+28+37=180

\displaystyle b+65=180

\displaystyle b=115

Example Question #1 : How To Find An Angle In An Acute / Obtuse Triangle

An isosceles triangle has an angle whose measure is \displaystyle 70^{\circ }.

What could be the measures of one of its other angles?

(a) \displaystyle 40^{\circ }

(b)  \displaystyle 55^{\circ }

(c) \displaystyle 70^{\circ }

Possible Answers:

(c) only

(a), (b), or (c)

(b) only

(a) or (c) only

(a) only

Correct answer:

(a), (b), or (c)

Explanation:

By the Isosceles Triangle Theorem, an isosceles triangle has two congruent interior angles. There are two possible scenarios if one angle has measure \displaystyle 70^{\circ }:

Scenario 1: The other two angles are congruent to each other. The degree measures of the interior angles of a triangle total \displaystyle 180^{\circ }, so if we let \displaystyle x be the common measure of those angles:

\displaystyle x + x + 70 = 180

\displaystyle 2x+70 = 180

\displaystyle 2x= 110

\displaystyle x = 55

This makes (b) a possible answer.

Scenario 2: One of the other angles measures \displaystyle 70^{\circ } also, making (c) a possible answer. The degree measure of the third angle is

\displaystyle 180 - (70 + 70) = 180 - 140 = 40,

making (a) a possible answer. Therefore, the correct choice is (a), (b), or (c).

Example Question #9 : How To Find An Angle In An Acute / Obtuse Triangle

One of the interior angles of a scalene triangle measures \displaystyle 54^{\circ }. Which of the following could be the measure of another of its interior angles?

Possible Answers:

\displaystyle 54^{\circ }

\displaystyle 108^{\circ }

\displaystyle 63^{\circ }

\displaystyle 72^{\circ }

\displaystyle 126^{\circ }

Correct answer:

\displaystyle 108^{\circ }

Explanation:

A scalene triangle has three sides of different measure, so, by way of the Converse of the Isosceles Triangle Theorem, each angle is of different measure as well. We can therefore eliminate \displaystyle 54^{\circ } immediately. 

Also, if the triangle also has a \displaystyle 72^{\circ } angle, then, since the total of the degree measures of the angles is \displaystyle 180^{\circ }, it follows that the third angle has measure

\displaystyle 180 - (54+72) = 180 - 126 = 54 ^{\circ }.

Therefore, the triangle has two angles that measure the same, and \displaystyle 72^{\circ } can be eliminated.

Similarly, if the triangle also has a \displaystyle 63^{\circ } angle, then, since the total of the degree measures of the angles is \displaystyle 180^{\circ }, it follows that the third angle has measure

\displaystyle 180 - (54+63) = 180 - 117= 63 ^{\circ }.

The triangle has two angles that measure \displaystyle 63^{\circ }. This choice can be eliminated.

\displaystyle 126^{\circ } can be eliminated, since the third angle would have measure

\displaystyle 180 - (54+126) = 180 - 180= 0^{\circ },

an impossible situation since angle measures must be positive.

The remaining possibility is \displaystyle 108^{\circ }. This would mean that the third angle has measure

\displaystyle 180 - (54+108) = 180 - 162= 18^{\circ }.

The three angles have different measures, so the triangle is scalene. \displaystyle 108^{\circ } is the correct choice.

Example Question #111 : Properties Of Triangles

Given: \displaystyle \bigtriangleup ABC with \displaystyle m \angle A = 20^{\circ }, m \angle B = 32^{\circ }. Locate \displaystyle D on \displaystyle \overline{AB} so that \displaystyle \overrightarrow{CD} is the angle bisector of \displaystyle \angle ACB. What is \displaystyle m \angle CDB ?

Possible Answers:

\displaystyle 69^{\circ }

\displaystyle 79^{\circ }

\displaystyle 89^{\circ }

\displaystyle 84^{\circ }

\displaystyle 74^{\circ }

Correct answer:

\displaystyle 84^{\circ }

Explanation:

Angle bisector

Above is the figure described.

The measures of the interior angles of a triangle total \displaystyle 180^{\circ }, so the measure of \displaystyle \angle ACB is

\displaystyle m \angle ACB = 180^{\circ } -( m \angle A + m \angle B)

\displaystyle = 180^{\circ } -( 20^{\circ } + 32^{\circ })

\displaystyle = 180^{\circ } - 52^{\circ }

\displaystyle = 128^{\circ }

Since \displaystyle \overrightarrow{CD} bisects this angle, 

\displaystyle m \angle BCD= \frac{1}{2}m \angle ACB = \frac{1}{2} \cdot 128^{\circ } =64^{\circ }

and 

\displaystyle m \angle CDB = 180^{\circ } -( m \angle BCD + m \angle B)

\displaystyle = 180^{\circ } -( 64 ^{\circ } + 32^{\circ } )

\displaystyle = 180^{\circ } -96^{\circ }

\displaystyle = 84^{\circ }

 

Example Question #21 : Acute / Obtuse Triangles

Given: \displaystyle \bigtriangleup ABC with \displaystyle m \angle B = 74^{\circ }. \displaystyle D is located on \displaystyle \overline{AB} so that \displaystyle \overrightarrow{CD} bisects \displaystyle \angle ACB and forms isosceles triangle \displaystyle \bigtriangleup BCD.

Give the measure of \displaystyle \angle A.

Possible Answers:

\displaystyle 64^{\circ }

Insufficient information is given to answer the question.

\displaystyle 42^{\circ }

\displaystyle 74^{\circ }

\displaystyle 53^{\circ }

Correct answer:

\displaystyle 42^{\circ }

Explanation:

If \displaystyle \bigtriangleup BCD is isosceles, then by the Isosceles Triangle Theorem, two of its angles must be congruent. 

Case 1: \displaystyle m \angle B = m \angle BCD= 74^{\circ }

Since \displaystyle \overrightarrow{CD} bisects \displaystyle \angle ACB into two congruent angles, one of which must be \displaystyle m \angle BCD

\displaystyle m \angle ACB = 2 \cdot m \angle BCD = 2 \cdot 74^{\circ } = 148^{\circ }

However, this is impossible, since \displaystyle \angle ACB and \displaystyle \angle B are two angles of the original triangle; their total measure is

 \displaystyle m \angle ACB+ m \angle B = 148^{\circ }+ 74 ^{\circ } = 222 ^{\circ } > 180 ^{\circ }

Case 2: \displaystyle m \angle B = m \angle BDC= 74^{\circ }

Then, since the degree measures of the interior angles of a triangle total \displaystyle 180^{\circ },

\displaystyle m \angle BCD= 180^{\circ } - ( \angle B + m \angle BDC )

\displaystyle = 180^{\circ } - (74^{\circ } + 74^{\circ } )

\displaystyle = 180 ^{\circ } - 148^{\circ }

\displaystyle = 32^{\circ }

Since \displaystyle \overrightarrow{CD} bisects \displaystyle \angle ACB into two congruent angles, one of which must be \displaystyle m \angle BCD

\displaystyle m \angle ACB = 2 \cdot m \angle BCD = 2 \cdot 32^{\circ } = 64^{\circ }

and

\displaystyle m \angle A = 180^{\circ } - ( \angle B + m \angle ACB )

\displaystyle = 180^{\circ } - (74^{\circ } + 64^{\circ } )

\displaystyle = 180^{\circ } - 138^{\circ }

\displaystyle = 42^{\circ }

Case 3: \displaystyle m \angle BDC= m \angle BCD

Then

\displaystyle m \angle B = 180^{\circ } -(m \angle BDC+ m \angle BCD)

\displaystyle 74= 180^{\circ } -(m \angle BCD+ m \angle BCD)

\displaystyle 74= 180^{\circ } -2 \cdot m \angle BCD

\displaystyle 2 \cdot m \angle BCD = 106^{\circ }

\displaystyle m \angle BCD = 53^{\circ }

\displaystyle m \angle ACB = 2 \cdot m \angle BCD = 2 \cdot 53^{\circ } = 106^{\circ }

\displaystyle m \angle A = 180^{\circ } - ( \angle B + m \angle ACB )

\displaystyle = 180^{\circ } - ( 74^{\circ }+ 106^{\circ } )

\displaystyle = 0^{\circ }, which is not possible.

Therefore, the only possible measure of \displaystyle \angle A is \displaystyle 42^{\circ }.

 

Example Question #111 : Properties Of Triangles

The interior angles of a triangle measure \displaystyle x^{\circ } , \left ( x+ 26\right )^{\circ } , \left (2x+ 1\right )^{\circ }. Of these three degree measures, give the greatest.

Possible Answers:

This triangle cannot exist.

\displaystyle 77^{\circ }

\displaystyle 77\frac{1}{2} ^{\circ }

\displaystyle 64\frac{1}{4} ^{\circ }

\displaystyle 103^{\circ }

Correct answer:

\displaystyle 77\frac{1}{2} ^{\circ }

Explanation:

The degree measures of the interior angles of a triangle total 180 degrees, so 

\displaystyle x + (x+26) + (2x+ 1) = 180

\displaystyle x +x+ 2x + 26 + 1 = 180

\displaystyle 4x+27 = 180

\displaystyle 4x+27 - 27 = 180 - 27

\displaystyle 4x = 153

\displaystyle \frac{4x}{4} = \frac{153}{4}

\displaystyle x = 38 \frac{1}{4}

One angle measures \displaystyle 38\frac{1}{4}^{\circ }

The other two angles measure 

\displaystyle x+ 26 = 38\frac{1}{4} + 26 = 64\frac{1}{4} ^{\circ }

and 

.

We want the greatest of the three, or \displaystyle 77 \frac{1}{2} ^{\circ }.

 

 

Example Question #23 : Acute / Obtuse Triangles

\displaystyle \bigtriangleup ABC is a right triangle with right angle \displaystyle \angle A.  \displaystyle D is located on \displaystyle \overline{AB} so that, when \displaystyle \overline{CD} is constructed, isosceles triangles \displaystyle \bigtriangleup ADC and  \displaystyle \bigtriangleup BDC are formed.

What is the measure of \displaystyle \angle B?

Possible Answers:

\displaystyle 67\frac{1}{2}^{\circ }

\displaystyle 30^{\circ }

\displaystyle 45^{\circ }

\displaystyle 15^{\circ }

\displaystyle 22\frac{1}{2}^{\circ }

Correct answer:

\displaystyle 22\frac{1}{2}^{\circ }

Explanation:

The figure referenced is below:

Right triangles

Since \displaystyle \bigtriangleup ADC is an isosceles right triangle, its acute angles - in particular, \displaystyle \angle ADC - measure \displaystyle 45^{\circ } each. Since this angle forms a linear pair with \displaystyle \angle CDB:

\displaystyle m \angle CDB = 180^{\circ } - m \angle ADC = 180^{\circ } - 45 ^{\circ } = 135^{\circ }.

 \displaystyle \bigtriangleup BDC is also isosceles, so, by the Isosceles Triangle Theorem, it has two congruent angles. Since \displaystyle \angle CDB is obtuse, and no triangle has two obtuse angles:

\displaystyle m \angle BCD = m \angle B.

Also, \displaystyle \angle ADC is an exterior angle of \displaystyle \bigtriangleup BDC, whose measure is equal to the sum of those of its two remote interior angles, which are the congruent angles \displaystyle m \angle BCD = m \angle B. Therefore,

\displaystyle m \angle ADC = m \angle BCD + m \angle B

\displaystyle 45^{\circ }= m \angle B + m \angle B

\displaystyle 45^{\circ }=2 m \angle B

\displaystyle m \angle B = 22\frac{1}{2}^{\circ }

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