Trigonometric Functions: Trigonometric Values in All Four Quadrants

think icon Think & Click: Finding Cosine and Sine in Quadrant I

Now, you try. Complete the Think & Click activity by looking at each problem below, thinking about it, and then clicking on the question to reveal the solution.

Using the unit circle find the cosine and sine function of pi divided by 3 radians.
 

Draw the special right triangle.

P(cos 60°, sin 60°)

= right triangle with base angle equals to pi divided by 3, legs equal to 1 and square root of 3 and hypotenuse equal to 2

cosine of pi divided by 3 equals one-half, sine of pi divided by 3 equals square root of 3 divided by 2