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Grade 11Trigonometry

cos3x/cos^3x + sin3X/sin^3x is equal to? (a) 3cos2x.cosec2x (b) 3cot2x.coesc2x (c)12cot2xcosec2x (d)12tan2xsec2x

Profile image of Rajesh Kumar
12 Years agoGrade 11
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1 Answer

Profile image of Rinkoo Gupta
12 Years ago
(4cos^3x-3cosx)/cos^3x +(3sinx-4sin^3x)/sin^3x
4-3/cos^2x+3/sin^2x-4
=3[1/sin^2x-1/cos^2x]
=3[cos^2x-sin^2x]/sin^2xcos^2x
=12.cos2x/sin^2(2x)
=12cot2x.cosec2x (c)
Thanks & Regards
Rinkoo Gupta
AskIITians Faculty

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