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Let cosA+cosB=x,cos2A+cos2B=y,cos3A+cos3B=z,then which of the following is true |
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Answer» `cos^(2)A+cos^(2)B=1+ y/2` `y=2(cos^(2)A+cos^(2)B)-2` `:.cos^(2)A+cos^(2)B=1+y/2` `:' cos A.cosBB=1/4(2x^(2)-y-2)` and `z=-2x^(3)+3xy+3x` `:.2x^(3)+z=3x(y+1)` ltbrogt `xyz=0AA A` and `B` is not true |
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