Question

`cos(pi/24) = ?` `A.` `sin((11pi)/24)` `B.` `sin((23pi)/24)` `C.` `sec((23pi)/24)` `D.` `sec((11pi)/24)`

Answer 1

A

Explanation:

Trigonometric Identity:

`cos(x)=sin(pi/2-x)`

SO

`cos(pi/24)=sin(pi/2-pi/24)`

`cos(pi/24)=sin((12pi)/24-pi/24)`

`cos(pi/24)=sin((11pi)/24)` --> A is your answer