Evaluate cos(90 degrees )

Problem

cos(90^∘)

Solution

1. Identify the angle on the unit circle. The angle 90^∘ corresponds to the positive y-axis.

2. Determine the coordinates of the point on the unit circle at 90^∘ The coordinates are (0,1)

3. Apply the definition of the cosine function. On the unit circle, cos(θ) is equal to the x-coordinate of the point.

4. Extract the x-coordinate from the point (0,1) which is 0

Final Answer

cos(90^∘)=0

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