Question 855451
Hint: I'll get you started



( 7sin(2x) + 7cos(2x) )^2 = 49



7sin(2x) + 7cos(2x) = 7 or 7sin(2x) + 7cos(2x) = -7 ... <font color="blue">take the square root of both sides (don't forget about the plus/minus)</font>



sin(2x) + cos(2x) = 1 or sin(2x) + cos(2x) = -1 ... <font color="blue">divide everything by 7</font>