Monday, 16 January 2017

trigonometry - Trigonometric Identities: fracsin2theta1+costheta=1costheta



sin2θ1+cosθ=1cosθ




Right Side:
1cosθ either stays the same, or can be 11secθ



Left Side:
=sin2θ1+cosθ=1cos2θ1+cosθ=(1cosθ)(1+cosθ)1+cosθ=1cosθ



Is this correct?


Answer



Perhaps slightly simpler and shorter (FYI, what you did is correct):
sin2x1+cosx=1cosxsin2x=(1cosx)(1+cosx)sin2x=1cos2x


And since the last equality is just the trigonometric Pytahgoras Theorem we're done.


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