# Unit Circle

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Unit Circle

### Slide 2:

The Unit Circle is a tool that can be used to find the values of the trig functions of some of the most common angles. The Unit Circle is a circle with a radius of one. It is based the values of the trig functions of the angles in the special right triangles.

### Slide 3:

Note: the angles can be found by starting at “0” and adding 30, 15, 15, 30 – then repeat. You should memorize the 3 points in the 1st quadrant. The values at 0, 90, 180 and 270 are found by remembering that a unit circle has a radius of “1”. The coordinate of the point at 0 degrees is (1, 0) since it is over 1 and up 0. The radians follow a different pattern. The denominators beginning at the top and bottom are 2, 3, 4, 6. All numerators are pi. Numerator = denominator - 1 Num = denominator + 1 Num = 2den - 1 The other points can be found matching the pts across and then down.

### Slide 4:

In order to use the Unit circle, remember that the point represents (cos x, sin x). Find cos 330. Find the point at The first # in the point is the cos. cos 330 = Find sin 180. Find the point at 180. The second # is the sine. sin 180 = 0

### Slide 5:

Your Turn: Find the value of the following. Then click to check your answers. Sin 30 = Cos 315 = Sin 135 = Cos 240 =