Q. 235.0( 2 Votes )

Prove that :

sin θ .cos (90° - θ) + cos θ sin (90° - θ).

Answer :

Taking LHS = sin θ cos (90° - θ) + cos θ sin (90° - θ)

sin θ × sin θ + cos θ × cos θ [ Sin θ = cos (90° - θ) and cos θ = sin (90° - θ) ]


cos2 θ + sin2 θ [ cos2 θ + sin2 θ = 1]


= 1 = RHS


Hence Proved


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