Question
Evaluate the following integrals:
$\int\frac{1}{\sin\text{x}\cos^3\text{x}}\text{ dx}$

Answer

$\frac{1}{\sin\text{x}\cos^3\text{x}}=\frac{\sin^2\text{x}+\cos^2\text{x}}{\sin\text{x}\cos^3\text{x}}$
$=\frac{\sin\text{x}}{\cos^3\text{x}}+\frac{1}{\sin\text{x}\cos\text{x}}$
$=\tan\text{x}\sec^2\text{x}+\frac{\frac{1\cos^2\text{x}}{\sin\text{x}\cos\text{x}}}{\cos^2\text{x}}$
$=\tan\text{x}\sec^2\text{x}+\frac{\sec^2\text{x}}{\tan\text{x}}$
$\therefore\ \int\frac{1}{\sin\text{x}\cos^3\text{x}}\text{ dx}=\int\tan\text{x}\sec^2\text{x}\text{ dx}+\int\frac{\sec^2\text{x}}{\tan\text{x}}\text{ dx}$
Let $\tan\text{x}=\text{t}$
$\sec^2\text{x}\text{ dx}=\text{dt}$
$\int\frac{1}{\sin\text{x}\cos^3\text{x}}\text{ dx}=\int\text{t}\text{ dt}+\int\frac{1}{\text{t}}\text{ dt}$
$=\frac{\text{t}^2}{2}+\log|\text{t}|+\text{C}$
$=\frac{1}{2}\tan^2\text{x}+\log|\tan\text{x}|+\text{C}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Find the angle between the lines whose direction cosines are given by the equations:
$2l + 2m - n = 0, mn + ln + lm = 0$
Find the points of discontinuity, if any of the following function:
$\text{f(x)}=\begin{cases}|\text{x}|+3,&\text{if }\text{ x}\geq-3\\-2\text{x},&\text{if }-3<\text{ x}<3\\6\text{x}+2,&\text{if }\text{ x}>3\end{cases}$
Solve the following differential equation:
$(\text{x}^2-1)\frac{\text{dy}}{\text{dx}}+2(\text{x}+2)\text{y}=2(\text{x}+1)$
Solve the following systems of linear equations by cramer's rule:
3x + y = 19,
3x - y = 23
Solve the following initial value problems:
$\frac{\text{dy}}{\text{dx}}+\text{y}\tan\text{x}=2\text{x}+\text{x}^2\tan\text{x},\text{ y}(0)=1$
There are two types of fertilisers 'A' and 'B'. 'A' consists of 12% nitrogen and 5% phosphoric acid whereas 'B' consists of 4% nitrogen and 5% phosphoric acid. After testing the soil conditions, farmer finds that he needs at least 12kg of nitrogen and 12kg of phosphoric acid for his crops. If 'A' costs Rs. 10 per kg and 'B' cost Rs. 8 per kg, then graphically determine how much of each type of fertiliser should be used so that nutrient requiremnets are met at a minimum cost.
Find one-parameter families of solution curves of the following differential equation: (or solve the following differential equation)$\frac{\text{dy}}{\text{dx}}-\text{y}=\cos2\text{x}$
Evaluate the following integrals:$\int_{0}^\limits{\frac{\pi}{4}}\frac{\sin\text{x}+\cos\text{x}}{3+\sin2\text{x}}\text{ dx}$
Find the maximum and the minimum values, if any, without using derivaives of the following functions:$f(x) = (x - 1)^2+ 2$ on $R.$
Using integration, find the area of the following region:
$\Big\{(\text{x},\text{y}):\frac{\text{x}^2}{9}+\frac{\text{y}^2}{4}\leq1\leq\frac{\text{x}}{3}+\frac{\text{y}}{2}\Big\}$