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4.2 Notes.notebook Precalculus Sec 4.2 Unit Circle ­ the unit circle is a different way to look at the values of the trig functions compared to the right triangle. ­ it gives the values of sine and cosine for the common angles, from these values you can calculate the other trig functions. 1 4.2 Notes.notebook How the Unit Circle Works ­ the unit circle is centered at the origin and has a radius of 1, we rotate the point (1,0) counterclockwise for positive angles. ­ you don't need to do this every time, but to make sense of how the unit circle works, where ever the angle is, we draw a line perpendicular to the x­axis to form a right triangle. 2 4.2 Notes.notebook ­ make sure that the unit circle you have is correct (angles and coordinates), you will be able to use your unit circle for quizzes and tests. 3 4.2 Notes.notebook Example The homework will ask you to evaluate the sine, cosine, and tangent of the real number, it will use the notation t=an angle, ignore the t. Find the values of the angle using the unit circle (not the calculator). 4 4.2 Notes.notebook Example 5 4.2 Notes.notebook Example 6