Question 401136
{{{5cos (2x) - 3sin(2x) = sqrt(34)*((5/sqrt(34))*cos (2x) +(-3/sqrt(34))*sin(2x))}}}
Let {{{cos(alpha) = 5/sqrt(34)}}} and {{{sin(alpha) = -3/sqrt(34)}}}, where
{{{alpha }}} is in the 4th quadrant.
Then
{{{5cos (2x) - 3sin(2x) = sqrt(34)*cos(2x - alpha)}}}