a m p ; d y d x = sin x + y cos x sin x ⋅ cos x ( 1 cos x − sin x ⋅ sin x cos x ) a m p ; = sin x + y cos x sin x ( 1 − sin 2 x ) a m p ; d y d x = sec 2 x + y ⋅ 2 ( cosec 2 x ) a m p ; d y d x − 2 cosec ( 2 x ) ⋅ y = sec 2 x a m p ; d y d x + p ⋅ y = Q \begin{aligned}& \frac{d y}{d x}=\frac{\sin x+y \cos x}{\sin x \cdot \cos x\left(\frac{1}{\cos x}-\sin x \cdot \frac{\sin x}{\cos x}\right)} \\& =\frac{\sin x+y \cos x}{\sin x\left(1-\sin ^2 x\right)} \\& \frac{d y}{d x}=\sec ^2 x+y \cdot 2(\operatorname{cosec} 2 x) \\& \frac{d y}{d x}-2 \operatorname{cosec}(2 x) \cdot y=\sec ^2 x \\& \frac{d y}{d x}+p \cdot y=Q\end{aligned} am p ; d x d y = sin x ⋅ cos x ( c o s x 1 − sin x ⋅ c o s x s i n x ) sin x + y cos x am p ; = sin x ( 1 − sin 2 x ) sin x + y cos x am p ; d x d y = sec 2 x + y ⋅ 2 ( cosec 2 x ) am p ; d x d y − 2 cosec ( 2 x ) ⋅ y = sec 2 x am p ; d x d y + p ⋅ y = Q
I.F. = e ∫ p d x = e ∫ − 2 cosec ( 2 x ) d x \text { I.F. }=\mathrm{e}^{\int p \mathrm{dx}}=\mathrm{e}^{\int-2 \operatorname{cosec}(2 \mathrm{x}) \mathrm{dx}} I.F. = e ∫ p dx = e ∫ − 2 cosec ( 2 x ) dx
Let 2 x = t 2 \mathrm{x}=\mathrm{t} 2 x = t
2 d x d t = 1 2 \frac{\mathrm{dx}}{\mathrm{dt}}=1 2 dt dx = 1
d x = d t 2 \mathrm{dx}=\frac{\mathrm{dt}}{2} dx = 2 dt
= e − ∫ cosec ( t ) d t =\mathrm{e}^{-\int \operatorname{cosec}(\mathrm{t}) \mathrm{dt}} = e − ∫ cosec ( t ) dt
= e − ln ∣ tan t 2 ∣ =\mathrm{e}^{-\ln \left|\tan \frac{t}{2}\right|} = e − l n ∣ t a n 2 t ∣
= e − ln ∣ tan x ∣ = 1 ∣ tan x ∣ =\mathrm{e}^{-\ln |\tan x|}=\frac{1}{|\tan x|} = e − l n ∣ t a n x ∣ = ∣ t a n x ∣ 1
a m p ; y ( IF ) = ∫ Q ( I F ) d x + c a m p ; ⇒ y 1 ∣ tan x ∣ = ∫ sec 2 x ⋅ 1 ∣ tan x ∣ + c a m p ; y ⋅ 1 ∣ tan x ∣ = ∫ d t ∣ t ∣ + c for tan x = t a m p ; y ⋅ 1 ∣ tan x ∣ = ln ∣ t ∣ + c a m p ; y = ∣ tan x ∣ ( ln ∣ tan x ∣ + c ) a m p ; Put x = π 4 , y = 2 a m p ; 2 = ln 1 + c ⇒ c = 2 a m p ; y = ∣ tan x ∣ ( ln ∣ tan x ∣ + 2 ) a m p ; y ( π 3 ) = 3 ( ln 3 + 2 ) \begin{aligned}& y(\text { IF })=\int Q(I F) d x+c \\& \Rightarrow y \frac{1}{|\tan x|}=\int \sec ^2 x \cdot \frac{1}{|\tan x|}+c \\& y \cdot \frac{1}{|\tan x|}=\int \frac{d t}{|t|}+c \quad \text { for } \tan x=t \\& y \cdot \frac{1}{|\tan x|}=\ln |t|+c \\& y=|\tan x|(\ln |\tan x|+c) \\& \text { Put } x=\frac{\pi}{4}, y=2 \\& 2=\ln 1+c \Rightarrow c=2 \\& y=|\tan x|(\ln |\tan x|+2) \\& y\left(\frac{\pi}{3}\right)=\sqrt{3}(\ln \sqrt{3}+2)\end{aligned} am p ; y ( IF ) = ∫ Q ( I F ) d x + c am p ; ⇒ y ∣ tan x ∣ 1 = ∫ sec 2 x ⋅ ∣ tan x ∣ 1 + c am p ; y ⋅ ∣ tan x ∣ 1 = ∫ ∣ t ∣ d t + c for tan x = t am p ; y ⋅ ∣ tan x ∣ 1 = ln ∣ t ∣ + c am p ; y = ∣ tan x ∣ ( ln ∣ tan x ∣ + c ) am p ; Put x = 4 π , y = 2 am p ; 2 = ln 1 + c ⇒ c = 2 am p ; y = ∣ tan x ∣ ( ln ∣ tan x ∣ + 2 ) am p ; y ( 3 π ) = 3 ( ln 3 + 2 )