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Home > A2C > Chapter 8 > Lesson 8.1.6 > Problem 8-93

8-93.

You have seen that you can calculate values of the sine function using right triangles formed by a radius of the unit circle. Values of that result in or triangles are used frequently on exercises and tests because their sines and cosines can be found exactly, without using a calculator. You should learn to recognize these values quickly and easily. The same is true for values of cosθ and sinθ that correspond to the - and -intercepts of the unit circle.

The central angles that correspond to these “special” values of are . What these angles have in common is that they are all multiples of , and some of them are also multiples of .

Copy and complete a table like the one below for all special angles between .

Degrees

Radians

Recall that  is  radians.  Since is  of ,   is  of , or .

All of the 'special' values of are multiples of either .
Knowing just these two values allows you to easily find the rest.

For Example, 

Degrees

Radians