omework Section 74 core 0 of 1 pt 7441 Write the expression

omework: Section 7.4 core: 0 of 1 pt 7.4.41 Write the expression as a sum or difference of trigonometric functions 8 sin 2x sin 4x 8sin 2x sin 4x =

Solution

given 8sin2x sin4x

use identity sinAsinB = 1/2 [ cos(A-B) - cos(A+B) ]

A=2x B=40

8sin2x sin4x = 8[ 1/2 [ cos(2x-4x) - cos(2x+4x) ]]

= 4[cos2x - cos6x]