Trigonometry : Trigonometry

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #1 : Law Of Sines

What is the measure of  in  below? Round to the nearest tenth of a degree.

Triangle def

Possible Answers:

Correct answer:

Explanation:

The law of sines tells us that , where ab, and c are the sides opposite of angles AB, and C. In , these ratios can be used to find :

Example Question #1 : Law Of Sines

Find the length of the line segment  in the triangle below.

Round to the nearest hundredth of a centimeter.

Triangle

Possible Answers:

Correct answer:

Explanation:

The law of sines states that 

.

In this triangle, we are looking for the side length c, and we are given angle A, angle B, and side b. The sum of the interior angles of a triangle is ; using subtraction we find that angle C.

We can now form a proportion that includes only one unknown, c:

Solving for c, we find that 

.

Example Question #1 : Law Of Sines

In the triangle below, , and . What is the length of side  to the nearest tenth?

Triangle abc

Possible Answers:

Correct answer:

Explanation:

First, find . The sum of the interior angles of a triangle is , so , or .

Using this information, you can set up a proportion to find side b:

 

Example Question #1 : Law Of Sines

In the triangle below, , and .

Triangle abc

What is the length of side a to the nearest tenth?

Possible Answers:

Correct answer:

Explanation:

To use the law of sines, first you must find the measure of . Since the sum of the interior angles of a triangle is .

Law of sines:

Example Question #11 : Law Of Sines

 

 

Construction02

The triangle above has side lengths 3, 4, and 6. The angle opposite the side of length 6 measures 117.28 degrees, rounded to the nearest hundredth. Angle  is opposite the side of length 3. What is the measure of , rounded to the nearest hundredth of a degree?

Possible Answers:

Correct answer:

Explanation:

Because the angle with measure 117.28 degrees is opposite the side of length 6, and angle  is opposite the side of length 3, we can use the Law of Sines to solve for the measure of .

Example Question #12 : Law Of Sines

Find the length of side a using the law of sines. All angles are in degrees.

Tri

Possible Answers:

Correct answer:

Explanation:

The law of sines states that, given a triangle with sides a, b, and c and angles A, B, and C opposite to the corresponding sides,

Tri

Since the sides and angles given are directly opposite, we can use the law of sines.

Solving for a, we get

Evaluating the expression, we find that 

Example Question #82 : Triangles

Find the measure of angle A.

Tri3

Possible Answers:

Correct answer:

Explanation:

The law of sines states that, given a triangle, the following relationship is always true:

where ab, and c are sides and A, B, and C are the angles opposite to the sides.

This problem does not give us the length of the side opposite to the angle we want to find, so we have to find it indirectly.

We start by finding the measure of the unmarked angle, which we'll represent as B:

Solving for , we get

Now that we have the measures of two angles, we can find the measure of the third by the theorem:

Example Question #14 : Law Of Sines

Find the length of side .

12

Possible Answers:

Correct answer:

Explanation:

13

Recall the Law of Sines:

Start by finding the value of angle :

Plug in the given values into the Law of Sines:

Rearrange the equation to solve for :

Make sure to round to two places after the decimal.

Example Question #83 : Triangles

6

Find the length of side 

Possible Answers:

Correct answer:

Explanation:

13

Recall the Law of Sines:

Start by finding the value of angle :

Plug in the given values into the Law of Sines:

Rearrange the equation to solve for :

Make sure to round to two places after the decimal.

Example Question #13 : Law Of Sines

8

Find the length of side .

Possible Answers:

Correct answer:

Explanation:

13

Recall the Law of Sines:

Start by finding the value of angle :

Plug in the given values into the Law of Sines:

Rearrange the equation to solve for :

Make sure to round to two places after the decimal.

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