Tag: trigonometry

Questions Related to trigonometry

$\dfrac{\cos (45^0+A)-\cos(45^0-A)}{\sin(120^0+A)-\sin(120^0-A)}=?$

  1. $2$

  2. $\sqrt{2}$

  3. $2\sqrt{2}$

  4. $2/\sqrt{2}$


Correct Option: A

if $A=30$ then the value of $\cos 2A$ is

  1. $1$

  2. $0$

  3. $1/2$

  4. $\surd {3}/2$


Correct Option: A

$(1+\tan 5^{o})(1+\tan 10^{o})(1+\tan 15^{o}).....(1+\tan 45^{o})$ is equal to

  1. $!$

  2. $32$

  3. $2$

  4. $0$


Correct Option: A

$sin 12^o\sin\ 24^o\sin\ 48^o\sin\ 84^o$=

  1. $\cos 20^o\cos 40^o\cos 60^o\cos 80^o$

  2. $\sin 20^o\sin 40^o\sin 60^o\sin 80^o$

  3. $\dfrac{3}{15}$

  4. $\dfrac{5}{16}$


Correct Option: A

$\tan 5\tan 25\tan 30\tan 65 \tan 85$ is equal to

  1. $3$

  2. $\surd {3}$

  3. $1$

  4. $\dfrac {1}{\surd {3}}$


Correct Option: A

$\tan 20 ^ { \circ } + \tan 40 ^ { \circ } + \sqrt { 3 } \tan 20 ^ { \circ } \tan 40 ^ { \circ }$  is equal to

  1. $\dfrac { \sqrt { 3 } } { 2 }$

  2. $\dfrac { \sqrt { 3 } } { 4 }$

  3. $\sqrt { 3 }$

  4. $1$


Correct Option: A

If $\alpha =685^o$, then $(\cos\alpha -\sin\alpha)$ is equivalent to?

  1. $-\cos 35^o-\sin 35^o$

  2. $-\cos 35^o +\sin 35^o$

  3. $\cos 35^o-\sin 35^o$

  4. $\cos 35^o+\sin 35^o$


Correct Option: A

The distance between $A ( \cos \theta , \sin \theta )$ and $B ( - \sin \theta , \cos \theta )$ is

  1. 1

  2. $2 + 2 \sin \theta$

  3. $1 + \sin \theta$

  4. $\sqrt { 2 }$


Correct Option: D
Explanation:

Given $A(\cos \theta,\sin \theta)$ and $B(-\sin \theta,\cos \theta)$

Distance between $AB=\sqrt{(\cos \theta+\sin \theta)^2+(\sin \theta-\cos \theta)^2}=\sqrt{\cos^2 \theta+\sin ^2 \theta+2\sin \theta\cos \theta+\cos^2\theta+\sin ^2 \theta-2\sin \theta\cos \theta}=\sqrt{1+1}=\sqrt{2}$

$\dfrac  { 1 tan^{ 1 } 45^{ 2 }}{ 1 tan^{ 1 } 45^{ 0 } }$

  1. $tan 90^{ 0 }$

  2. $sin 45^{ 0 }$

  3. $sin 90^{ 0 }$

  4. $cos 90^{ 0 }$


Correct Option: A

$\displaystyle3\tan^2{30^\circ}+\frac{4}{3}\cos^2{30^\circ}-2\sin^2{45^\circ}-\frac{1}{3}\sin^2{60^\circ}$ is equal to__________________.

  1. $\displaystyle\frac{1}{4}$

  2. $\displaystyle\frac{3}{4}$

  3. $1$

  4. $0$


Correct Option: B
Explanation:

Given 


$3\tan ^230+\dfrac 43\cos ^230-2\sin ^245-\dfrac 13\sin ^260$

$=3\left(\dfrac 1{\sqrt 3}\right)^2+\dfrac 43\left(\dfrac {\sqrt 3}2 \right)^2-2\left(\dfrac 1{\sqrt 2}\right)^2-\dfrac 13\left(\dfrac {\sqrt 3}2\right)^2$

$=1+1-1-\dfrac 14$

$= \dfrac 34$