LECTURE NOTES OF CONTINUITY AND DIFFERENTIABILITY (PART 4)

3. cos2x = 2COS 5. cos 2x = cos x— sin x 2 tan x 7. tan2x= I—tan x 9. cos3x = 4cos x—3cosx Example l. Differentiate the following w.r.t. 'x' : -l l+cosx (i) cos Solution. (i) Let dy (ii) Let -l - cos = cos 1 I + cosx - cos 2cos — — cos 3 cosx + sin x (ii) I +'2 cos cos— — cosx+l = cos cos sin x Ans, -l (Nficosx+sinx) = cos = cos ................
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