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If `x =cos alpha+cos beta-cos(alpha+beta)` and `y=4 sin.(alpha)/(2)sin.(beta)/(2)cos.((alpha+beta)/(2))`, then (x-y) equals |
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Answer» Correct Answer - A `y=4 sin.(alpha)/(2)sin.(beta)/(2)cos((alpha+beta)/(2))` `=2[cos.(alpha-beta)/(2)-cos.(alpha+beta)/(2)]cos((alpha+beta)/(2))` `= cos alpha + cos beta - (1+cos (alpha + beta))=x-1` `rArr x-y=1` `cos 5^(@)cos 20^(@)+cos 35^(@)cos 50^(@)` |
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