08 - Calculate Sin, Cos & Tan w/ Unit Circle in Radians - Part 1

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In this lesson, we will learn how to use the unit circle to calculate the sin, cos, or tangent of an angle in radians. The first step is to draw the angle and determine which quadrant the angle lies. Next, we find the reference angle, which is the angle from the terminal ray of our angle to the nearest x-axis. Finally, we use the reference angle to find the sine and cosine values in quadrant 1 and insert a negative or positive sign on the front of the answer depending on the quadrant that the angle lies in. In order to calculate the tangent, we simply first find the sine and cosine, the divide the two numbers to calculate the tangent of the angle.