How do you use the composite argument properties to transform the left side of the equation to a single function of a composite argument?

Question

cosxcos50°-sinxsin50°=.7

then solve algebraeically with the domain

x∈[0°,360°]

Answer 1

cos(a+b) = cos(a)*cos(b)-sin(a)*sin(b)

cos(x+50) = cos(x)*cos(50)-sin(x)*sin(50)

cos(x+50) = 0.7

x+50 = cos^-1(.7) = 45.573, 314.427, 405.573

x = -4.427, 264.427, 355.573

x = 264.427, 355.573