In this lesson we use a combination of techniques that you have learned in previous lessons to find the exact values of trigonometric ratios for angles larger than 90 degrees.

We talk about how to find the values of sin, cos and tan in quadrants 2, 3 or 4, given the value of sin, cos or tan in the first quadrant. e.g. sin(150 degrees)=sin(30 degrees).

In this lesson you learn how to express trigonometric ratios as exact values. For example, instead of typing cos30 in the calculator to get 0.866, after doing this tutorial you will be able to write cos30 = sqrt(3)/2 without using the calculator.

In this lesson we discuss the differences in the sign and values of sine, cosine and tangent theta in the four quadrants. Quadrant 1 is from 0 to 90 degrees, quadrant 2 is between 90 to 180, quadrant 3 is between 180 to 270 degrees and quadrant 4 is between 270 to 360 degrees. …

In this lesson we talk about how to obtain values for sine and cosine bigger than 90 degrees and the reasoning behind those values.

In this lesson, we talk about why it is that, for any point on the unit circle, x=cos(theta) and y=sin(theta).