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यदि `3tan theta tan phi =1`,साबित करें कि `2cos ( theta + varphi )= cos ( theta-varphi) ` |
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Answer» प्रश्न से, `3 tan theta tan varphi =1 ` या `cot theta , cot varphi = 3 ` या `(cos theta cos varphi )/(sin theta sin varphi ) = (3)/(1)` compenendo और dividendo से, `(cos theta cos varphi +sin thetasinvarphi)/(cos thetacos varphi -sin theta sin varphi) = ( 3+1)/(3-1) ` या `(cos (theta-varphi))/(cos(theta+varphi))=2` या `2cos (theta+varphi) = cos(theta-varphi)` |
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