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Question
Evaluate:
`cos[tan^-1 (3/4)]`
Solution
Let `tan^-1 (3/4) = theta`
`3/4` = tan θ
tan θ = `3/4`
∴ cos θ = `4/5`
`[because theta = tan^-1 3/4]`
Now `cos[tan^-1 (3/4)] = cos theta = 4/5`
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