Question

Evaluate cos(40°-theta)-sin(50°+theta)+(cos^2 40°+cos^2 50°)÷(sin^2 40°+sin^2 50°)

Answer 1

cos(40-x) - sin(50-x) + (cos^2 40° + sin^2 50°)/(sin^2 40° + cos^2 50°)
= cos(40-x) - cos(40-x) + (cos^2 40° + cos^2 40°)/(sin^2 40° + sin^2 50°)
(Formula used: sin(90-x) = cosx; cos(90-x)=sinx)
= 0 + 1/1= 1