# HSPT Math : How to find the measure of an angle

## Example Questions

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

What is the supplementary angle to ?

Explanation:

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

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

What angle is complement to ?

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

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?

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.

### Example Question #12 : How To Find The Measure Of An Angle

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 are the odds against the spinner landing while pointing inside one of the blue regions?

8 to 5

13 to 11

17 to 7

5 to 2

17 to 7

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.

Two of the blue sectors are each one third of one quarter-circle, and thus are

of one circle.

The other two blue sectors are each one fourth of one quarter-circle, and thus are

of one circle.

Therefore, the total angle measure comprises

of a circle. This makes  the correct probability. As odds, this translates to

, or  odds against the spinner landing in blue.

### Example Question #12 : How To Find The Measure Of An Angle

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 are the odds against the spinner landing while pointing inside the purple region?

9 to 1

13 to 1

7 to 1

11 to 1

11 to 1

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 purple region is one third of one quarter of a circle, or, equvalently,

of a circle, so its central angle is  of the total measures of the angles of the sectors. This makes  the probability of the spinner stopping inside the purple region; this translates to

or  odds against this occurrence.

### Example Question #14 : How To Find The Measure Of An Angle

In parallelogram . Give the measure of  in terms of .

Explanation:

and  are a pair of adjacent angles of the parallelogram, and as such, they are supplementary - that is, their degree measures total 180. Therefore,

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

The measures of the angles of  are as follows:

Is this triangle acute, obtuse, right, or nonexistent?

cannot exist

is an acute triangle

is a right triangle

is an obtuse triangle

is an acute triangle

Explanation:

The sum of the measures of the angles of a triangle is 180 degrees, so solve for  in the equation:

All three angles measure less than 90 degrees and are therefore acute angles; that makes  an acute triangle.

### Example Question #13 : How To Find The Measure Of An Angle

If you have a right triangle, what is the measure of the two of the angles if they are equal?

Explanation:

The total degrees of the angles in a triangle are .

Since it is a right triangle, one of the three angles must be

That leaves you with  for the other two angles .

If they are equal, you just divide the remaining degrees by  to get .

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

If you have a right triangle with an angle measuring 45 degrees, what is the third angle measurement?

Explanation:

A right triangle has one 90 degree angle and all three angles must equal 180 degrees.

To find the answer, just subtract the two angles you have from the total to get

The angle we have are,

.

Substituting these into the formula results in the solution.

.

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