Evaluate cos(-270 degrees )

Problem

cos(−270)

Solution

1. Apply the even-odd identity for the cosine function, which states cos(−θ)=cos(θ)

cos(−270)=cos(270)

2. Identify the position of 270 on the unit circle. This angle corresponds to the negative y-axis.

270=(3*π)/2* radians

3. Determine the coordinates at 270 on the unit circle. The coordinates (x,y) are (0,−1)

(x,y)=(0,−1)

4. Evaluate the cosine using the x-coordinate of the point on the unit circle.

cos(270)=0

Final Answer

cos(−270)=0

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