Precalculus : Trigonometric Applications

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #6 : Law Of Cosines And Sines

Lc1c

What is the measurement of side  using the Law of Cosines? Round to the nearest tenth.

Possible Answers:

Correct answer:

Explanation:

The Law of Cosines for side  is,

 .

Plugging in the information we know, the formula is,

 .

Then take the square of both sides: .

Finally, round to the appropriate units: .

Example Question #11 : Law Of Cosines And Sines

Use the Law of Cosines to solve for the specified variable.

Pcq1

Solve for . Round to the nearest tenth.

Possible Answers:

None of these answers are correct.

Correct answer:

Explanation:

Law of Cosines

Therefore...

After rounding...

Example Question #51 : Trigonometric Applications

Use the Law of Sines to find  in the following triangle.

9

(Not drawn to scale.)

Possible Answers:

Correct answer:

Explanation:

We use the Law of Sines to solve this problem

 

we plug in  

 

solving for  we get:

 

Example Question #52 : Trigonometric Applications

Use the Law of Sines to find .

10 

(Not drawn to scale.)

Possible Answers:

Correct answer:

Explanation:

We use the Law of Sines to solve this problem: 

where 

 

We plug in the values that we will need:

               Notice that we did not use 

 

Solve for  we get:

Example Question #53 : Trigonometric Applications

Which of the following are the missing sides of the triangle?

11

Possible Answers:

None of the above

Correct answer:

Explanation:

In order to solve this problem, we need to find . We do so by remembering the sum of the angles in a triangle is :

 

We can now use the Law of Sines to find the missing sides.

   

         which is II.

  

   

        which is III.

 

Our answers are then II and III

Example Question #15 : Law Of Cosines And Sines

Which of the following are the missing sides of the triangle?

 12

Possible Answers:

None of the above

Correct answer:

Explanation:

In order to solve this problem, we need to find  

Since all the angles of a triangle add to , we can easily find it:

We can now use the Law of Sines to find the missing sides:

   

      which is I.

 

   

      which is III.

 

Our answers are then I and III.

Example Question #16 : Law Of Cosines And Sines

Solve the triangle using the Law of Sines:

Law_of_sines__aas_

Possible Answers:

None of the other answers

Correct answer:

Explanation:

First we need to know what the Law of Sines is:

Looking at the triangle, we know c, C, and B. We can either solve for side b, using the law, or angle A using our knowledge that the interior angles of a triangle must add up to be 180.

Now all that's left is to find side a:

Example Question #17 : Law Of Cosines And Sines

Use the Law of Sines to solve for the specified variable.

Pcq2

Solve for . Round to the nearest tenth.

Possible Answers:

None of these answers are correct.

Correct answer:

Explanation:

Law of Sines

 

Therefore...

 

After rounding...

Example Question #18 : Use The Laws Of Cosines And Sines

Pcq2

Solve for c using Law of Sines, given:

Round to the nearest tenth.

Possible Answers:

None of these answers are correct.

Correct answer:

Explanation:

Law of Sines

 

Therefore...

After rounding...

Example Question #54 : Trigonometric Applications

Triangle_700

Given  and , what is the measurement of  to the nearest degree?

Possible Answers:

Correct answer:

Explanation:

Using the information we have, we can solve for 

.

Plugging in what we know, we have: 

.

Then, solve for 

.

Simplify, then solve for  which means .

Therefore, after rounding to the nearest degree, .

To solve for , subtract  and  from .

Therefore, .

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