If y = 1 + sin   θ + cos   θ 1 + sin   θ - cos   θ ,   show   that ,   d y d θ + 1 1 - cos   θ = 0 .

Dear student

We have,y=1+sinθ+cosθ1+sinθ-cosθDifferentiate ot w.r.t.θ., we getdy=cosθ-sinθ1+sinθ-cosθ-1+sinθ+cosθcosθ+sinθ1+sinθ-cosθ2dy=cosθ+cosθsinθ-cos2θ-sinθ-sin2θ+sinθcosθ-cosθ-sinθ-sinθcosθ-sin2θ-cos2θ-sinθcosθ1+sin2θ+cos2θ+2sinθ-2sinθcosθ-2cosθdy=-2sinθ-22+2(sinθ-cosθ)-2sinθcosθdy=-21+sinθ21+sinθ-cosθ-sinθcosθdy=-1+sinθ11+sinθ-cosθ1+sinθdy=-1+sinθ1+sinθ1-cosθdy+11-cosθ=0
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