Question

Prove the following identities:

$\frac{\sin\theta}{(1+\cos\theta)}+\frac{(1+\cos^2\theta)}{\sin\theta}=2\text{cosec}\theta$

Answer

$\text{L.H.S.}=\frac{\sin\theta}{(1+\cos\theta)}+\frac{(1+\cos^2\theta)}{\sin\theta}$

$=\frac{\sin\theta(1-\cos\theta)}{(1+\cos\theta)(1-\cos\theta)}+\frac{1+\cos\theta}{\sin\theta}$

$=\frac{\sin\theta(1-\cos\theta)}{1-\cos^2\theta}+\frac{1+\cos\theta}{\sin\theta}$

$=\frac{\sin\theta(1-\cos\theta)}{\sin\theta}+\frac{1+\cos\theta}{\sin\theta}$

$=\frac{(1-\cos\theta)}{\sin\theta}+\frac{1+\cos\theta}{\sin\theta}$

$=\frac{1-\cos\theta+1+\cos\theta}{\sin\theta}$

$=\frac{2}{\sin\theta}$

$=2\text{cosec}\theta$

$=\text{R.H.S.}$

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

Prove the following trigonometric identities.
$\Big(\frac{1}{\sec^2\theta-\cos^2\theta}+\frac{1}{\text{cosec}^2\theta-\sin^2\theta}\Big)\sin^2\theta\cos^2\theta=\frac{1-\sin^2\theta\cos^2\theta}{2+\sin^2\theta\cos^2\theta}$
Two dice are rolled once. Find the probability of getting such numbers on two dice whose product is a perfect square.
The $24^{\text {th }}$ term of an $A.P.$ is twice its $10^{\text {th }}$ term. Show that its $72^{\text {nd }}$ term is 4 times its $15^{\text {th }}$ term.
A two-digit number is $4$ more than $6$ times the sum of its digits. If $18$ is subtracted from the number, the digits are reversed. Find the number.
Show graphically that each of the following given systems of equations has infinitely many solutions:
$2x + 3y = 6, 4x + 6y = 12$
The difference of two natural numbers is $3$ and the difference of their reciprocals is $\frac{3}{28}.$ Find the numbers.
A piece of cloth costs Rs. $35$. If the piece were $4\ m$ longer and each meter costs Rs. one less, the cost would remain unchanged. How long is the piece?
A milk container is made of metal sheet in the shape of frustum of cone whose volume is $10459\ cm^3$. The radii of its lower and upper circular ends are $8\ cm$ and $20\ cm$ respectively. Find the cost of metal sheet used in making the container at the rate of $Rs.\ 1.40\ per\ cm^2$. $\Big(\text{use}\ \pi=\frac{22}{7}\Big)$
Prove the following trigonometric identities.
If $\text{T}_\text{n}=\sin^\text{n}\theta+\cos^\text{n}\theta,$ porve that $\frac{\text{T}_3-\text{T}_5}{\text{T}_1}=\frac{\text{T}_5-\text{T}_7}{\text{T}_3}.$
A vertical pole of length $6\ m$ casts a shadow $4\ m$ long on the ground and at the same time a tower casts a shadow $28\ m$ long. Find the height of the tower.