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Question
Evaluate the following:
`cot^-1{cot ((21pi)/4)}`
Solution
We know that
cot-1 (cot θ) = θ, (0, π)
We have
`cot^-1{cot (21pi)/4}=cot^-1[cot(5pi+pi/4)]`
`=cot^-1(cot pi/4)`
`=pi/4`
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