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If `x=sectheta-costheta` and `y=sec^n theta- cos^n theta` then show that `(x^2+4)((dy)/(dx))^2=n^2(y^2+4)`A. 8B. 16C. 64D. 49 |
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Answer» Correct Answer - C `(dy)/(dx)=(((dy)/(d theta)))/(((dx)/(d theta)))=(8sec^(8) theta tan theta+8cos^(7) thetasin theta)/(sec thetatan theta+sin theta)` `=(8 tan theta(sec^(8)theta+cos^(8)theta)^(2))/(tan theta (sec theta+ cos theta))` `therefore" "((dy)/(dx))^(2)=(64(sec^(8)theta+cos^(8)theta)^(2))/((sec theta+cos theta)^(2))` `=(64[(sec^(8)theta-cos^(8)theta)^(2)+4])/([(sec theta-cos theta)^(2)+4])` `=(64(y^(2)+4))/((x^(2)+4))` `therefore" "((x^(2)+4)/(y^(2)+4))((dy)/(dx))^(2)=64` |
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