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Grade 10Trigonometry

cosx+cosy+cosz+cos(x+y+z)
=4cos(x+y/2)cos(y+z/2)cos(z+x/2)

Profile image of Pratham Sahu
8 Years agoGrade 10
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1 Answer

Profile image of Arun
8 Years ago
Dear student
 
(Cos x + cos y ) + ( cosz + cos (x+y+z))
 = 2 cos (x+y/2) cos (x- y/2) + 2 cos (x+y/2 + z) cos (x+y/2)
 = 2 cos (x+y/2) [cos (x-y/2)+ cos (x+y/2 + z)]
 = 2 cos ( x+ y/2 ) * 2 cos (x + z/2) cos (y+z/2)
 = 4 cos (x+y/2) cos (y+z/2) cos (x+z/2)
 
Regards
Arun

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