NCERT Class XI Mathematics - Limits and Derivatives - Solutions

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Question : 63
Total: 72
a+bsinx
c+dcosx
Solution:  
Let f (x) =
a+bsinx
c+dcosx
... (i)
Differentiating (i) with respect to x, we get
d
dx
(f (x)) =
(a+bsinx)(c+dcosx)(a+bsinx)(c+dcosx)
(c+dcosx)2

=
bcosx(c+dcosx)(a+bsinx)(dsinx)
(c+dcosx)2

=
bccosx+bdcos2x+adsinx+bdsin2x
(c+dcosx)2

=
bccosx+bd(cos2x+sin2x)+adsinx
(c+dcosx)2

=
bccosx+asdsinx+bd
(c+dcosx)2

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