just doing some past papers and there is a type of question that I can't understand..ever!

for example:

solve the equation: sin(θ - 30°) = 0.7 in the interval 0°≤ θ ≤ 360°

solve the equation: cosx=0.3 in the interval 0 ≤ x ≤ 2π

can anyone help me please??

thank you!