- #1

kingboy

- 5

- 0

## Homework Statement

show that the expression 8 cos^2 x -6 sin x cos x +2 may be expressed in the form rcos (2x+α)+s ,and determine the value of the constants r,s and α.hence ,or otherwise, find the greatest and latest values of the expression as x varies.

## Homework Equations

cos 2x=cos^2x-sin^2x ,sin2a=2 sinxcosx ,acos x-bsinx=rcos(x+α)

## The Attempt at a Solution

8 cos^2 x -6 sin x cos x +2=8(cos 2x+sin^2x)+3(2 sinxcosx)+2=?????