Give all radian solutions to

$\displaystyle cos(7x)cos(2x) + sin(7x)sin(2x) = 1/2$

The only place where i know where to begin is

$\displaystyle cos(2x) = 2cos^2 - 1$

would i need to reduce the cos(7x) like

$\displaystyle cos(7x) = cos(4x + 3x)$

until i get down to cos(2x)?

so i could use the identity

Can anyone help me get started on this beast?