Trigonometry : Trigonometry

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #13 : Angles In Different Quadrants

Which two angles are both in the same quadrant?

Possible Answers:

and

and

and

 and

and

Correct answer:

and

Explanation:

First lets identify the different quadrants.

Quadrant I:

Quadrant II: 

Quadrant III: 

Quadrant IV: 

Now looking at our possible answer choices, we will add or subtract  until we get the reduced fraction of the angle. This will tell us which quadrant the angle lies in.

 thus in quadrant III. 

 thus in quadrant III.

Therefore,

 and  is the correct answer.

Example Question #13 : Angles In Different Quadrants

Which angle is in quadrant II?

Possible Answers:

Correct answer:

Explanation:

 

First lets identify the different quadrants.

Quadrant I:

Quadrant II: 

Quadrant III: 

Quadrant IV: 

The correct answer,, is coterminal with .

We can figure this out by adding , or equivalently to get , or we can count thirds of pi around the unit circle clockwise. Either way, it is the only angle that ends in the second quadrant.

Example Question #72 : Angles

In which angle would a  angle terminate in?

Possible Answers:

Quadrant III

Quadrant IV

Quadrant I

Between quadrants

Quadrant II

Correct answer:

Quadrant IV

Explanation:

One way to uncover which quadrant this angle lies is to ask how many complete revolutions this angle makes by dividing it by 360 (and rounding down to the nearest whole number).

With a calculator we find that  makes  full revolutions. Now the key lies in what the remainder the angle makes with  revolutions:

, therefore our angle lies in the fourth quadrant.

Alternatively, we could find evaluate  and .

The former (sine) gives us a negative number whereas the latter (cosine) gives a positive. The only quadrant in which sine is negative and cosine is positive is the fourth quadrant.

 

Example Question #531 : Trigonometry

Which quadrant does  belong?

Possible Answers:

IV

I

III

II

Correct answer:

II

Explanation:

Step 1: Define the quadrants and the angles that go in:

QI:


QII:


QIII:


QIV:



Step 2: Find the quadrant where  is:

The angle is located in QII (Quadrant II)

Example Question #532 : Trigonometry

The angle  is in which quadrant?

Possible Answers:

Quadrant II

Quadrant IV

Quadrant I

Quadrant III

Correct answer:

Quadrant I

Explanation:

First, using the unit circle, we can see that the denominator has a four in it, which means it is a multiple of .

We want to reduce the angle down until we can visualize which quadrant it is in. You can subtract  away from the angle each time (because that is just one revolution, and we end up at the same spot).

If you subtract away  twice, you are left with , which is in quadrant I. 

.

Example Question #533 : Trigonometry

Which of the following angles lies in the second quadrant?

Possible Answers:

Correct answer:

Explanation:

The second quadrant contains angles between  and , plus those with additional multiples of .  The angle  is, after subtracting , is simply , which puts it in the second quadrant.

Example Question #1 : Trigonometry

Find the value of the trigonometric function in fraction form for triangle .

Triangle

What is the cosine of ?

Possible Answers:

Correct answer:

Explanation:

The cosine of an angle is the value of the adjacent side over the hypotenuse.

Therefore:

Example Question #2 : Sin, Cos, Tan

What is the value of ?

Possible Answers:

Correct answer:

Explanation:

Solve each term separately.

Add both terms.

Example Question #2 : Sin, Cos, Tan

Determine the value of .

Possible Answers:

Correct answer:

Explanation:

Rewrite  in terms of sines and cosines.

Simplify the complex fraction.

Example Question #2 : Sin, Cos, Tan

Find the value of .

Possible Answers:

Correct answer:

Explanation:

To find the value of , solve each term separately.

Sum the two terms.

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