HSPT Math : Geometry

Study concepts, example questions & explanations for HSPT Math

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Example Questions

Example Question #1 : Acute / Obtuse Triangles

In a given triangle, the angles are in a ratio of 1:3:5.  What size is the middle angle?

Possible Answers:

45^{\circ}

60^{\circ}

75^{\circ}

20^{\circ}

90^{\circ}

Correct answer:

60^{\circ}

Explanation:

Since the sum of the angles of a triangle is 180^{\circ}, and given that the angles are in a ratio of 1:3:5, let the measure of the smallest angle be , then the following expression could be written:

x+3x+5x=180

9x=180

x=20

 

If the smallest angle is 20 degrees, then given that the middle angle is in ratio of 1:3, the middle angle would be 3 times as large, or 60 degrees.

Example Question #1 : Right Triangles

The measure of 3 angles in a triangle are in a 1:2:3 ratio. What is the measure of the middle angle?

Possible Answers:
30
90
60
45
Correct answer: 60
Explanation:

The angles in a triangle sum to 180 degrees. This makes the middle angle 60 degrees.

Example Question #3 : How To Find The Measure Of An Angle

Call the three angles of a triangle 

The measure of  is twenty degrees greater than that of ; the measure of  is thirty degrees less than twice that of . If  is the measure of , then which of the following equations would we need to solve in order to calculate the measures of the angles?

Possible Answers:

Correct answer:

Explanation:

The measure of  is twenty degrees greater than the measure  of , so its measure is 20 added to that of  - that is, .

The measure of  is thirty degrees less than twice that of . Twice the measure of  is , and thirty degrees less than this is 30 subtracted from  - that is, .

The sum of the measures of the three angles of a triangle is 180, so, to solve for  - thereby allowing us to calulate all three angle measures - we add these three expressions and set the sum equal to 180. This yields the equation:

Example Question #4 : How To Find The Measure Of An Angle

Call the three angles of a triangle 

The measure of  is forty degrees less than that of ; the measure of  is ten degrees less than twice that of . If  is the measure of , then which of the following equations would we need to solve in order to calculate the measures of the angles?

Possible Answers:

Correct answer:

Explanation:

The measure of  is forty degrees less than the measure  of , so its measure is 40 subtracted from that of  - that is, .

The measure of  is ten degrees less than twice that of . Twice the measure of  is , and ten degrees less than this is 10 subtracted from  - that is, .

The sum of the measures of the three angles of a triangle is 180, so, to solve for  - thereby allowing us to calulate all three angle measures - we add these three expressions and set the sum equal to 180. This yields the equation:

Example Question #4 : How To Find The Measure Of An Angle

Two interior angles of a triangle adds up to  degrees.  What is the measure of the other angle?

Possible Answers:

Correct answer:

Explanation:

The sum of the three angles of a triangle add up to 180 degrees.  Subtract 64 degrees to determine the third angle.

Example Question #1 : How To Find The Measure Of An Angle

What is  of the measure of a right angle?

Possible Answers:

Correct answer:

Explanation:

A right angle has a measure of .  One fifth of the angle is:

Example Question #6 : How To Find The Measure Of An Angle

What angle is complementary to ?

Possible Answers:

Correct answer:

Explanation:

To find the other angle, subtract the given angle from  since complementary angles add up to .

The complementary is:

Example Question #11 : How To Find The Measure Of An Angle

What is the supplementary angle to ?

Possible Answers:

Correct answer:

Explanation:

Supplementary angles add up to . In order to find the correct angle, take the known angle and subtract that from .

Example Question #1 : Solve Simple Equations For An Unknown Angle In A Figure: Ccss.Math.Content.7.G.B.5

What angle is complement to ?

Possible Answers:

Correct answer:

Explanation:

The complement to an angle is ninety degrees subtract the angle since two angles must add up to 90.  In this case, since we are given the angle in radians, we are subtracting from  instead to find the complement.  The conversion between radians and degrees is:  

Reconvert the fractions to the least common denominator.

Reduce the fraction.

Example Question #11 : How To Find The Measure Of An Angle

Spinner target 2

The above diagram shows a spinner. The radius of the smaller quarter-circles is half that of the larger quarter-circles.

A player spins the above spinner. What is the probability that the spinner will stop while pointing inside a red region?

Possible Answers:

Correct answer:

Explanation:

The size of the regions does not matter here. What matters is the angle measurement, or, equivalently, what part of a circle each sector is.

The two smaller red regions each comprise one fourth of one fourth of a circle, or 

 circle.

The two larger red regions each comprise one third of one fourth of a circle, or

 circle.

Therefore, the total angle measure comprises

of a circle.

This makes  the correct probability.

 

 

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