LFM Pure

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Let $\frac { \tan ( \alpha - \beta + \gamma ) } { \tan ( \alpha + \beta - \gamma ) } = \frac { \tan \beta } { \tan \gamma }$. Then
(A) $\sin ( \beta - \gamma ) = \sin ( \alpha - \beta )$.
(B) $\sin ( \alpha - \gamma ) = \sin ( \beta - \gamma )$.
(C) $\sin ( \beta - \gamma ) = 0$.
(D) $\sin 2 \alpha + \sin 2 \beta + \sin 2 \gamma = 0$
Let $\frac { \tan 3 \theta } { \tan \theta } = k$. Then
(A) $k \in ( 1 / 3,3 )$
(B) $k \notin ( 1 / 3,3 )$
(C) $\frac { \sin 3 \theta } { \sin \theta } = \frac { 2 k } { k - 1 }$.
(D) $\frac { \sin 3 \theta } { \sin \theta } > \frac { 2 k } { k - 1 }$
Suppose $x , y \in ( 0 , \pi / 2 )$ and $x \neq y$. Which of the following statements is true?
(a) $2 \sin ( x + y ) < \sin 2 x + \sin 2 y$ for all $x , y$.
(b) $2 \sin ( x + y ) > \sin 2 x + \sin 2 y$ for all $x , y$.
(c) There exist $x , y$ such that $2 \sin ( x + y ) = \sin 2 x + \sin 2 y$.
(d) None of the above.
32. A man from the top of a 100 metres high tower sees a car moving towards the tower at an angle of depression of 300 . After some time, the angle of depression becomes 600. The distance (in metres) travelled by the car during this time is :
(A) $100 \sqrt { 3 }$
(B) $( 200 \sqrt { } 3 ) / 3$
(C) $( 100 \sqrt { } 3 ) / 3$
(D) $200 \sqrt { } 3$
jee-advanced 2017 Q45 Half-Angle Formula Evaluation View
Let $\alpha$ and $\beta$ be nonzero real numbers such that $2 ( \cos \beta - \cos \alpha ) + \cos \alpha \cos \beta = 1$. Then which of the following is/are true?
[A] $\tan \left( \frac { \alpha } { 2 } \right) + \sqrt { 3 } \tan \left( \frac { \beta } { 2 } \right) = 0$
[B] $\sqrt { 3 } \tan \left( \frac { \alpha } { 2 } \right) + \tan \left( \frac { \beta } { 2 } \right) = 0$
[C] $\tan \left( \frac { \alpha } { 2 } \right) - \sqrt { 3 } \tan \left( \frac { \beta } { 2 } \right) = 0$
[D] $\sqrt { 3 } \tan \left( \frac { \alpha } { 2 } \right) - \tan \left( \frac { \beta } { 2 } \right) = 0$
The value of the limit $$\lim_{x \rightarrow \frac{\pi}{2}} \frac{4\sqrt{2}(\sin 3x + \sin x)}{\left(2\sin 2x \sin\frac{3x}{2} + \cos\frac{5x}{2}\right) - \left(\sqrt{2} + \sqrt{2}\cos 2x + \cos\frac{3x}{2}\right)}$$ is $\_\_\_\_$
jee-advanced 2022 Q1 3 marks Multi-Step Composite Problem Using Identities View
Let $\alpha$ and $\beta$ be real numbers such that $- \frac { \pi } { 4 } < \beta < 0 < \alpha < \frac { \pi } { 4 }$. If $\sin ( \alpha + \beta ) = \frac { 1 } { 3 }$ and $\cos ( \alpha - \beta ) = \frac { 2 } { 3 }$, then the greatest integer less than or equal to
$$\left( \frac { \sin \alpha } { \cos \beta } + \frac { \cos \beta } { \sin \alpha } + \frac { \cos \alpha } { \sin \beta } + \frac { \sin \beta } { \cos \alpha } \right) ^ { 2 }$$
is $\_\_\_\_$ .
Suppose $\theta$ and $\phi ( \neq 0 )$ are such that $\sec ( \theta + \phi )$, $\sec \theta$ and $\sec ( \theta - \phi )$ are in A.P. If $\cos \theta = k \cos \left( \frac { \phi } { 2 } \right)$ for some $k$, then $k$ is equal to
(1) $\pm \sqrt { 2 }$
(2) $\pm 1$
(3) $\pm \frac { 1 } { \sqrt { 2 } }$
(4) $\pm 2$
The value of $\cos 255 ^ { \circ } + \sin 195 ^ { \circ }$ is
(1) $\frac { \sqrt { 3 } - 1 } { 2 \sqrt { 2 } }$
(2) $\frac { \sqrt { 3 } - 1 } { \sqrt { 2 } }$
(3) $- \frac { \sqrt { 3 } - 1 } { \sqrt { 2 } }$
(4) $\frac { \sqrt { 3 } + 1 } { \sqrt { 2 } }$
If $\tan\left(\frac{\pi}{4} + \frac{\theta}{2}\right) = \tan^3\left(\frac{\pi}{4} + \frac{\alpha}{2}\right)$, then $\sin\theta = $:
(1) $\frac{\sin\alpha(3 + \sin^2\alpha)}{1 + 3\sin^2\alpha}$
(2) $\frac{\sin\alpha(3 - \sin^2\alpha)}{1 + 3\sin^2\alpha}$
(3) $\frac{\sin\alpha(3 + \cos^2\alpha)}{1 + 3\cos^2\alpha}$
(4) $\frac{\sin\alpha(3 - \cos^2\alpha)}{1 + 3\cos^2\alpha}$
If $A > 0 , B > 0$ and $A + B = \frac { \pi } { 6 }$, then the minimum positive value of $( \tan A + \tan B )$ is :
(1) $\sqrt { 3 } - \sqrt { 2 }$
(2) $4 - 2 \sqrt { 3 }$
(3) $\frac { 2 } { \sqrt { 3 } }$
(4) $2 - \sqrt { 3 }$
If $5 ( \tan ^ { 2 } x - \cos ^ { 2 } x ) = 2 \cos 2 x + 9$, then the value of $\cos 4 x$ is:
(1) $- \frac { 7 } { 9 }$
(2) $- \frac { 3 } { 5 }$
(3) $\frac { 1 } { 3 }$
(4) $\frac { 2 } { 9 }$
If $\sin ^ { 4 } \alpha + 4 \cos ^ { 4 } \beta + 2 = 4 \sqrt { 2 } \sin \alpha \cos \beta , \alpha , \beta \in [ 0 , \pi ]$, then $\cos ( \alpha + \beta ) - \cos ( \alpha - \beta )$ is equal to
(1) - 1
(2) $- \sqrt { 2 }$
(3) $\sqrt { 2 }$
(4) 0
If $\cos(\alpha + \beta) = \frac{3}{5}$, $\sin(\alpha - \beta) = \frac{5}{13}$ and $0 < \alpha, \beta < \frac{\pi}{4}$, then $\tan 2\alpha$ is equal to:
(1) $\frac{21}{16}$
(2) $\frac{63}{52}$
(3) $\frac{33}{52}$
(4) $\frac{63}{16}$
The value of $\cos ^ { 3 } \left( \frac { \pi } { 8 } \right) \cdot \cos \left( \frac { 3 \pi } { 8 } \right) + \sin ^ { 3 } \left( \frac { \pi } { 8 } \right) \cdot \sin \left( \frac { 3 \pi } { 8 } \right)$ is:
(1) $\frac { 1 } { \sqrt { 2 } }$
(2) $\frac { 1 } { 2 \sqrt { 2 } }$
(3) $\frac { 1 } { 2 }$
(4) $\frac { 1 } { 4 }$
jee-main 2020 Q56 Half-Angle Formula Evaluation View
If $L = \sin^2\left(\frac{\pi}{16}\right) - \sin^2\left(\frac{\pi}{8}\right)$ and $M = \cos^2\left(\frac{\pi}{16}\right) - \sin^2\left(\frac{\pi}{8}\right)$
(1) $L = -\frac{1}{2\sqrt{2}} + \frac{1}{2}\cos\frac{\pi}{8}$
(2) $L = \frac{1}{4\sqrt{2}} - \frac{1}{4}\cos\frac{\pi}{8}$
(3) $M = \frac{1}{4\sqrt{2}} + \frac{1}{4}\cos\frac{\pi}{8}$
(4) $M = \frac{1}{2\sqrt{2}} + \frac{1}{2}\cos\frac{\pi}{8}$
If $0 < x , y < \pi$ and $\cos x + \cos y - \cos ( x + y ) = \frac { 3 } { 2 }$, then $\sin x + \cos y$ is equal to:
(1) $\frac { 1 } { 2 }$
(2) $\frac { \sqrt { 3 } } { 2 }$
(3) $\frac { 1 - \sqrt { 3 } } { 2 }$
(4) $\frac { 1 + \sqrt { 3 } } { 2 }$
$16 \sin \left( 20 ^ { \circ } \right) \sin \left( 40 ^ { \circ } \right) \sin \left( 80 ^ { \circ } \right)$ is equal to
(1) $\sqrt { 3 }$
(2) $2 \sqrt { 3 }$
(3) 3
(4) $4 \sqrt { 3 }$
The value of $\cos \left( \frac { 2 \pi } { 7 } \right) + \cos \left( \frac { 4 \pi } { 7 } \right) + \cos \left( \frac { 6 \pi } { 7 } \right)$ is equal to
(1) $- 1$
(2) $- \frac { 1 } { 2 }$
(3) $- \frac { 1 } { 3 }$
(4) $- \frac { 1 } { 4 }$
The value of $2\sin\frac{\pi}{22}\sin\frac{3\pi}{22}\sin\frac{5\pi}{22}\sin\frac{7\pi}{22}\sin\frac{9\pi}{22}$ is equal to:
(1) $\frac{1}{16}$
(2) $\frac{5}{16}$
(3) $\frac{7}{16}$
(4) $\frac{3}{16}$
The value of $2\sin 12^\circ - \sin 72^\circ$ is
(1) $\frac{\sqrt{5}(1 - \sqrt{3})}{4}$
(2) $\frac{1 - \sqrt{5}}{8}$
(3) $\frac{\sqrt{3}(1 - \sqrt{5})}{2}$
(4) $\frac{\sqrt{3}(1 - \sqrt{5})}{4}$
$96 \cos\frac{\pi}{33} \cos\frac{2\pi}{33} \cos\frac{4\pi}{33} \cos\frac{8\pi}{33} \cos\frac{16\pi}{33}$ is equal to
(1) 3
(2) 1
(3) 4
(4) 2
Let $g(x) = f(x) + f(1 - x)$ and $f ^ { \prime \prime } (x) > 0 , x \in (0,1)$. If $g$ is decreasing in the interval $(0 , \alpha)$ and increasing in the interval $(\alpha , 1)$, then $\tan ^ { - 1 } (2\alpha) + \tan ^ { - 1 } \left( \frac { 1 } { \alpha } \right) + \tan ^ { - 1 } \left( \frac { \alpha + 1 } { \alpha } \right)$ is equal to
(1) $\pi$
(2) $\frac { 5\pi } { 4 }$
(3) $\frac { 3\pi } { 4 }$
(4) $\frac { 3\pi } { 2 }$
Suppose $28 - p,\ p,\ 70 - \alpha,\ \alpha$ are the coefficient of four consecutive terms in the expansion of $(1 + x)^n$. Then the value of $2\alpha - 3p$ equals
(1) 7
(2) 10
(3) 4
(4) 6
If $\sum _ { r = 1 } ^ { 13 } \left\{ \frac { 1 } { \sin \left( \frac { \pi } { 4 } + ( r - 1 ) \frac { \pi } { 6 } \right) \sin \left( \frac { \pi } { 4 } + \frac { r \pi } { 6 } \right) } \right\} = a \sqrt { 3 } + b , a , b \in \mathbf { Z }$, then $a ^ { 2 } + b ^ { 2 }$ is equal to :
(1) 10
(2) 4
(3) 2
(4) 8