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यदि `cosec theta+cot theta=m,` सिद्ध कीजिए कि `(m^(2)-1)/(m^(2)+1)=cos theta.` |
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Answer» यहाँ `cosec theta +cot theta=m` `implies(cosec theta+cot theta)^(2)=m^(2)` `impliescosec ^(2)theta+cot ^(2)theta+2cosec theta cot theta=m^(2)` यहाँ, `L.H.S.=(m^(2)-1)/(m^(2)+1)=(cosec ^(2)theta+cot^(2)theta+2 cosec theta cottheta-1)/(cosec ^(2)theta+cot^(2)theta+cosec theta cot theta+1)` `=(cot ^(2)theta+cot ^(2)theta+2 cosec theta cot theta)/(cosec ^(2)+cosec ^(2)theta+2cosec theta cot theta)` `=(2cot^(2)theta+2cosec thetacot theta)/(2 cosec ^(2)theta+2 cosec theta cot theta)=(2cot theta(cot theta+cosec theta))/(2 cosec theta(cosec theta+cot theta))=(cot theta)/(cosec theta)` `=((cos theta)/(sin theta))/((1)/(sin theta))=(cos theta)/(sin theta)xx(sin theta)/(1)=cos theta=R.H.S.` |
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