Six Trigonometric Values in a Unit Circle

Based on the unit circle, what is the value of cos?

• y/r

• x/r

• r/y

• y/x

Based on the unit circle, what is the value of tan?

• y/r

• x/r

• r/y

• y/x

Answer explanation

The cos is always the x coordinate divided by the radius. With the unit circle that radius is 1

Based on the unit circle, what is the value of sin?

• y/r

• x/r

• r/y

• y/x

Answer explanation

The sin is always the y coordinate divided by the radius. With the unit circle that radius is 1.

What is cos 60°?

• ½

• ^√3/₂

• ^√2/₂

• 1

What is sin 45°?

• 1
• ^√3/₂
• ½
• ^√2/₂

What is sin 30°?

• ^√3/₂

• 1

• ½

• ^√2/₂

What are the coordinates of 210° on the unit circle?

• (−√3/2, −1/2)

• (√3/2, −1/2)

• (−√3/2, 1/2)

• (−1/2,−√3/2 )

What is the reference angle for -30°?

• 150°

• 30°

• 80°

• 60°

Answer explanation

Every angle is measured from the positive part of the x-axis to its terminal line (the line that determines the end of the angle) traveling counterclockwise. If you want to find the reference angle, you have to find the smallest possible angle formed by the x-axis and the terminal line, going either clockwise or counterclockwise.

All six trigonometric functions are positive in the first quadrant.

• True

• False

Find sec(π/4)

• 0

• -2

• √2

• -√3