Find the Exact Value cos(18pi)
Problem
Solution
Identify the periodicity of the cosine function, which has a period of
2*π Determine the number of full rotations by dividing the angle by
2*π Calculate the quotient:
18*π/2*π=9 Since this is an integer, the angle18*π is coterminal with0 Evaluate the cosine of the coterminal angle
0 Recall that
cos(0)=1
Final Answer
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