`cos(tan^(-1)(3/4)) =`A. `3/5`B. `4/5`C. `4/9`D. none of these

1.	`cos(tan^(-1)(3/4)) =`A. `3/5`B. `4/5`C. `4/9`D. none of these
Answer» Correct Answer - B Let `tan^(-1)3/4=x`, where `x in (-pi/2, pi/2)`. `therefore tanx=3/4` and since `x in (-pi/2, pi/2)`, we have `cosx gt 0`. `therefore cosx=1/(secx)=1/sqrt(1+tan^(2)x)=1/sqrt(1+9/16)=4/5`. `therefore cos(tan^(-1)3/4)=cosx=4/5`.

Discussion

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