intregation of 1/1+cotx
Answers
Answer:
(x/2) - log (sinx+cosx)+c
Step-by-step explanation:
To find---->
_______
1
∫----------------- dx
1 + cotx
Solution----->
________
let
1
I= ∫---------------dx
1+ cotx
1
=∫--------------------------dx
1 + cosx/ sinx
1
=∫-------------------------------dx
sinx +cosx/sinx
sinx
=∫-------------------------------dx
sinx +cosx
2sinx
=∫----------------------------------dx
2(sinx +cosx)
sinx +sinx
=∫---------------------------------dx
2( sinx + cosx)
(sinx+cosx)+(sinx-cosx)
=∫------------------------------------------ dx
2 ( sinx + cosx)
(sinx+ cosx)-(cosx-sinx)
=∫-------------------------------------------dx
2 (sinx+cosx)
(sinx+cosx) ( cosx -sinx)
=∫---------------------- -∫--------------------------- dx
2 ( sinx +cosx) 2 (sinx +cosx)
1 cosx -sinx
=--- ∫ 1 dx - ∫-----------------------dx
2 2( sinx +cosx)
cosx -sinx
= x/2 - ∫-----------------------dx
2( sinx+cosx)
now let
sinx+cosx =t
differentiating both sides
( cosx -sinx )dx =dt
now
dt
I=(x/2) -∫--------
t
=(x/2 ) - log t
=(x/2) - log(sinx +cosx)+c
Hope it helps you
Thanks for giving me chance to answer your question
here isthe solutuion,
∫ [ 1 / ( 1 + cos x/sin x ) ] dx
. = ∫ [ ( sin x ) / ( sin x + cos x ) ] dx
. = (1/2) • ∫ [ ( 2 sin x ) / ( sin x + cos x ) ] dx ...( Note This Step )
. = (1/2) • ∫ { [ ( sin x + cos x ) - ( cos x - sin x ) ] / ( sin x + cos x ) } dx ... This Too
. = (1/2) • { ∫ 1 dx - ∫ [ ( cos x - sin x ) / ( sin x + cos x ) ] dx }
. = (1/2) • { x - ∫ (1/u) du }, ... where ... u = sin x + cos x
. = ( x/2 ) - (1/2)· ln | u | + C
. = ( x/2 ) - (1/2)· ln | sin x + cos x | + C .................ans
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