Answer: C
\(sin(45°+θ)=cos(2θ-30°)\)
\(=sin[90°-(2θ-30°) ] \)
\(∴ 45°+θ=90°-(2θ-30°)\)
or, \(45°+θ=60°-2θ \)
or, \(θ+2θ=60°-45° \)
or, \(θ=15° \)
\(sin(45°+θ)=cos(2θ-30°)\)
\(=sin[90°-(2θ-30°) ] \)
\(∴ 45°+θ=90°-(2θ-30°)\)
or, \(45°+θ=60°-2θ \)
or, \(θ+2θ=60°-45° \)
or, \(θ=15° \)