Trigonometry : Unit Circle and Radians

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #42 : Radians And Conversions

Convert  into degrees.

Possible Answers:

Correct answer:

Explanation:

To convert from radians to degrees, you must multiply the angle by  to cancel the  units.

This will get you 

Example Question #212 : New Sat Math Calculator

Convert  to degrees:

Possible Answers:

Correct answer:

Explanation:

To convert radians to degrees, we need to multiply the given radians by .

 

Example Question #41 : Radians

Give your answer in terms of .

Convert   to radians:

Possible Answers:

Correct answer:

Explanation:

To convert degrees to radians, we need to multiply the given degree by .

To simplify, we get:

Example Question #61 : Unit Circle And Radians

Convert  to radians.

Possible Answers:

Correct answer:

Explanation:

To convert between degrees and radians, multiply by  or .

Since we start in degrees, we use :

which simplifies to .

Example Question #51 : Radians And Conversions

Convert  radians into degrees.

Possible Answers:

Correct answer:

Explanation:

Recall the definition of "radians" derived from the unit circle:

The quantity of radians given in the problem is . All that is required to convert this measure into degrees is to denote the unknown angle measure in degrees by  and set up a proportion equation using the aforementioned definition relating radians to degrees:

Cross-multiply the denominators in these fractions to obtain:

or

.

Canceling like terms in these equations yields

Hence, the correct angle measure of  in degrees is .

Example Question #1 : Angles In The Unit Circle

What are the ways to write 360o and 720o in radians?

 

Possible Answers:

Correct answer:

Explanation:

 on the unit circle. 

 on the unit circle.

Example Question #1 : Angles In The Unit Circle

Which of the following is not an angle in the unit circle?

Possible Answers:

Correct answer:

Explanation:

The unit circle is in two increments: , etc. and , etc. The only answer choice that is not a multiple of either  or  is .

Example Question #1 : Angles In The Unit Circle

What is the equivalent of , in radians?

Possible Answers:

Correct answer:

Explanation:

To convert from degrees to radians, use the equality 

 or .

From here we use  as a unit multiplier to convert our degrees into radians.

 

Example Question #1 : Angles In The Unit Circle

What is the value of

Possible Answers:

Correct answer:

Explanation:

To help with this one, draw a 45-45-90 triangle. With legs equal to 1 and a hypotenuse of .

Then, use the definition of tangent as opposite over adjacent to find the value.

Since the legs are congruent, we get that the ratio is 1. 

Example Question #2 : Angles In The Unit Circle

What is ?

Possible Answers:

Correct answer:

Explanation:

Recall that on the unit circle, sine represents the y coordinate of the unit circle.

Then, since we are at 90˚, we are at the positive y axis, the point (0,1).

At this point on the unit circle, the y value is 1.

Thus  .

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