### Mathematics - Trigonometry

#### Question - 1

If sin A = sin B and cos A = cos B, then

• A $sin{1\over2}(A+B)=0$
• B $sin{1\over2}(A-B)=0$
• C $cos{1\over2}(A+B)=0$
• D $cos{1\over2}(A-B)=0$

#### Question - 2

If cos $\theta$ + sin $\theta$ = $\sqrt2$ cos $\theta$ then cos $\theta$ - sin $\theta$ =

• A $\sqrt2$ cos $\theta$
• B $\sqrt2$ sin $\theta$
• C $\sqrt2$ (cos $\theta$ + sin $\theta$)
• D None of these

#### Question - 3

The equation sin2 $\theta$ = $x^{2}+y^{2}\over2xy$,is posible if

• A x=y
• B x=-y
• C 2x=y
• D None of these

#### Question - 4

If sin3 x sin 3x =$\sum _{ m=0 }^{ n }{ = } { c }_{ m }$  cos mx ,where c0,c1,c2,......cn $\neq$ 0, is an identify in x then n =

• A 5
• B 6
• C 7
• D 8

#### Question - 5

The value of the expression $1-\frac { { \sin { } }^{ 2 }y }{ 1+\cos { \quad y } } +\frac { 1+\cos { \quad y } }{ sin\quad y } -\frac { sin\quad y }{ 1-\cos { \quad y } }$,is

• A 0
• B 1
• C sin y
• D cos y

#### Question - 6

If sin A,cos A,tan A are in G.P..,then cot6A - cot2A  , equals

• A 0
• B -1
• C 1
• D None of these

#### Question - 7

If sin x + sin2x =1 ,then value of cos2x+cos4x is

• A 1
• B 2
• C 1.5
• D None of these

#### Question - 8

The period of the function 4cos3 $\theta$-3cos $\theta$ is

• A $\pi\over3$
• B $\pi\over4$
• C $2\pi\over3$
• D None of these

#### Question - 9

If $xcos\theta = y cos\left( \theta +\frac { 2\pi }{ 3 } \right) =zcos\left( \theta +\frac { 4\pi }{ 3 } \right)$ ,then value of xy+yz+zx is

• A 0
• B 1
• C 2
• D None of these

#### Question - 10

The value of tan 3x-tan 2x-tan x is

• A tan x tan 2x tan 3x
• B - tan x tan 2x tan 3x
• C tan x tan 2x - tan 2x tan 3x -tan 3x tan x
• D None of these