Question

Evaluate the following:

`cos(tan^-1  24/7)`

Answer 1

`cos(tan^-1  24/7)=cos[cos^-1  1/sqrt(1+(24/7)^2)]`    `[therefore tan^-1x=cos^-1  1/sqrt(1+z^2)]`

`=cos[cos^-1  1/sqrt(1+576/49)]`

`=cos[cos^-1  1/(25/7)]`

`=cos[cos^-1  7/25]`

`=7/25`