If sinΦ=(Sinx+Siny)/1+Cosx.Cosy then prove that CosΦ=Cosx.Cosy/(1+Cosx.Cosy) answer of this question??

1 Answer
Feb 5, 2018

#sinphi=(sinx+siny)/(1+cosx cdot cosy)#
#=>sin^2phi=(sinx+siny)^2/(1+cosx cdot cosy)^2#
#=>1-cos^2phi=(sin^2x+sin^2y+2sinxsiny)/(1+2cosxcosy+cos^2xcos^2y)#
#=>cos^2phi=1-((sin^2x+sin^2y+2sinxsiny)/(1+2cosxcosy+cos^2xcos^2y))#
#=>cos^2phi=(1+2cosxcosy+cos^2xcos^2y-sin^2x-sin^2y-2sinxsiny)/(1+cosxcosy)^2#
#=>#

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