Question

How do you simplify cos(x - pi/2)?

Answer 1

`sinx`

Explanation:

We know that ,cos is an even function.`=>cos(-theta)=costheta`
`:.cos(x-pi/2)=cos(pi/2-x)=sinx`
OR
`cos(A-B)=cosAcosB+sinAsinB`
`cos(x-pi/2)=cosxcos(pi/2)+sinxsin(pi/2)`
`cos(x-pi/2)=cosx(0)+sinx(1)=0+sinx=sinx`