Q.

Find an acute angle θ when cosθ-sinθcosθ+sinθ=1-31+3


Ans.

(60°)

cosθ-sinθcosθ+sinθ=1-31+3

Dividing the numerator and denominator of LHS by cosθ, we get

1-tanθ1+tanθ=1-31+3

Which on simplification (or comparison) gives

tanθ=3    θ=60°