LFM Pure

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Find the number of solutions of $\sec x + \tan x = 2\cos x$ in $[0, 2\pi]$.
(A) 0 (B) 1 (C) 2 (D) 3
In the triangle $A B C$, the angle $\angle B A C$ is a root of the equation $$\sqrt { 3 } \cos x + \sin x = 1 / 2$$ Then the triangle $A B C$ is
(A) obtuse angled
(B) right angled
(C) acute angled but not equilateral
(D) equilateral
The set of all solutions of the equation $\cos 2\theta = \sin \theta + \cos \theta$ is given by
(A) $\theta = 0$
(B) $\theta = n\pi + \frac{\pi}{2}$, where $n$ is any integer
(C) $\theta = 2n\pi$ or $\theta = 2n\pi - \frac{\pi}{2}$ or $\theta = n\pi - \frac{\pi}{4}$, where $n$ is any integer
(D) $\theta = 2n\pi$ or $\theta = n\pi + \frac{\pi}{4}$, where $n$ is any integer
The set of all solutions of the equation $\cos 2 \theta = \sin \theta + \cos \theta$ is given by
(A) $\theta = 0$
(B) $\theta = n \pi + \frac { \pi } { 2 }$, where $n$ is any integer
(C) $\theta = 2 n \pi$ or $\theta = 2 n \pi - \frac { \pi } { 2 }$ or $\theta = n \pi - \frac { \pi } { 4 }$, where $n$ is any integer
(D) $\theta = 2 n \pi$ or $\theta = n \pi + \frac { \pi } { 4 }$, where $n$ is any integer
isi-entrance 2016 Q35 4 marks Inverse trigonometric equation View
The value of $$\sin ^ { - 1 } \cot \left[ \sin ^ { - 1 } \left\{ \frac { 1 } { 2 } \left( 1 - \sqrt { \frac { 5 } { 6 } } \right) \right\} + \cos ^ { - 1 } \sqrt { \frac { 2 } { 3 } } + \sec ^ { - 1 } \sqrt { \frac { 8 } { 3 } } \right]$$ is
(A) 0
(B) $\pi / 6$
(C) $\pi / 4$
(D) $\pi / 2$
isi-entrance 2016 Q45 4 marks Inverse trigonometric equation View
The number of solutions of the equation $\sin^{-1} x = 2 \tan^{-1} x$ is
(A) 1
(B) 2
(C) 3
(D) 5
isi-entrance 2016 Q45 4 marks Inverse trigonometric equation View
The number of solutions of the equation $\sin ^ { - 1 } x = 2 \tan ^ { - 1 } x$ is
(A) 1
(B) 2
(C) 3
(D) 5
Find all pairs $( x , y )$ with $x , y$ real, satisfying the equations: $$\sin \left( \frac { x + y } { 2 } \right) = 0 , \quad | x | + | y | = 1$$
For a real number $\alpha$, let $S _ { \alpha }$ denote the set of those real numbers $\beta$ that satisfy $\alpha \sin ( \beta ) = \beta \sin ( \alpha )$. Then which of the following statements is true?
(A) For any $\alpha , S _ { \alpha }$ is an infinite set.
(B) $S _ { \alpha }$ is a finite set if and only if $\alpha$ is not an integer multiple of $\pi$.
(C) There are infinitely many numbers $\alpha$ for which $S _ { \alpha }$ is the set of all real numbers.
(D) $S _ { \alpha }$ is always finite.
The number of solutions of the equation $\sin ( 7 x ) + \sin ( 3 x ) = 0$ with $0 \leq x \leq 2 \pi$ is
(A) 9
(B) 12
(C) 15
(D) 18.
The set of all solutions of the equation $\cos 2 \theta = \sin \theta + \cos \theta$ is given by
(a) $\theta = 0$.
(b) $\theta = n \pi + \frac { \pi } { 2 }$, where $n$ is any integer.
(c) $\theta = 2 n \pi$ or $\theta = 2 n \pi - \frac { \pi } { 2 }$ or $\theta = n \pi - \frac { \pi } { 4 }$, where $n$ is any integer.
(d) $\theta = 2 n \pi$ or $\theta = n \pi + \frac { \pi } { 4 }$, where $n$ is any integer.
isi-entrance 2026 Q13 Inverse trigonometric equation View
The number of solutions of the equation $\sin ^ { - 1 } x = 2 \tan ^ { - 1 } x$ is
(a) 1 .
(B) 2 .
(C) 3 .
(D) 5 .
jee-advanced 1999 Q11 Inverse trigonometric equation View
11. The number of real solutions of $\tan - 1 \sqrt { } ( x ( x + 1 ) ) + \sin - 1 \sqrt { } ( x 2 + x + 1 ) = \pi / 2$ is:
(A) zero
(B) one
(C) two
(D) infinite
jee-advanced 2001 Q31 Tangent Lines and Tangent Lengths View
31. Let $P Q$ and $R S$ be tangents at the extremities of the diameter $P R$ of a circle of radius $r$. If PS and RQ intersect at a point X on the circumference of the circle, then 2 r equals :
(A) $\sqrt { } ( \mathrm { PQ } . \mathrm { RS } )$
(B) $( P Q + R S ) / 2$
(C) $( 2 \mathrm { PQ } \cdot \mathrm { RS } ) / ( \mathrm { PQ } + \mathrm { RS } )$
(D) $\sqrt { } ( ( P Q 2 + R S 2 ) / 2 )$
11. The number of integral values of $k$ for which the equation $7 \cos x + 5 \sin x = 2 k +$ 1 has a solution is
(A) 4
(B) 8
(C) 10
(D) 12
The number of solutions of the pair of equations $$2\sin^2\theta - \cos 2\theta = 0$$ $$2\cos^2\theta - 3\sin\theta = 0$$ in the interval $[0, 2\pi]$ is
(A) 0
(B) 1
(C) 2
(D) 4
The number of solutions of the equation $\sin^{-1}\left(\frac{x}{\sqrt{1+x^2}}\right) - \sin^{-1}\left(\frac{1}{\sqrt{1+x^2}}\right) = \sin^{-1}\left(\frac{x-1}{\sqrt{1+(x-1)^2}}\right) - \sin^{-1}\left(\frac{1}{\sqrt{1+(x-1)^2}}\right)$ is
(A) 0
(B) 1
(C) 2
(D) infinite
For $0<\theta<\frac{\pi}{2}$, the solution(s) of $$\sum_{m=1}^{6}\operatorname{cosec}\left(\theta+\frac{(m-1)\pi}{4}\right)\operatorname{cosec}\left(\theta+\frac{m\pi}{4}\right)=4\sqrt{2}$$ is(are)
(A) $\frac{\pi}{4}$
(B) $\frac{\pi}{6}$
(C) $\frac{\pi}{12}$
(D) $\frac{5\pi}{12}$
The number of values of $\theta$ in the interval $\left( - \frac { \pi } { 2 } , \frac { \pi } { 2 } \right)$ such that $\theta \neq \frac { \mathrm { n } \pi } { 5 }$ for $\mathrm { n } = 0 , \pm 1 , \pm 2$ and $\tan \theta = \cot 5 \theta$ as well as $\sin 2 \theta = \cos 4 \theta$ is
The number of all possible values of $\theta$, where $0 < \theta < \pi$, for which the system of equations $$\begin{gathered} ( y + z ) \cos 3 \theta = ( x y z ) \sin 3 \theta \\ x \sin 3 \theta = \frac { 2 \cos 3 \theta } { y } + \frac { 2 \sin 3 \theta } { z } \\ ( x y z ) \sin 3 \theta = ( y + 2 z ) \cos 3 \theta + y \sin 3 \theta \end{gathered}$$ have a solution $\left( x _ { 0 } , y _ { 0 } , z _ { 0 } \right)$ with $y _ { 0 } z _ { 0 } \neq 0$, is
For $x \in (0, \pi)$, the equation $\sin x + 2\sin 2x - \sin 3x = 3$ has
(A) infinitely many solutions
(B) three solutions
(C) one solution
(D) no solution
The number of distinct solutions of the equation $$\frac { 5 } { 4 } \cos ^ { 2 } 2 x + \cos ^ { 4 } x + \sin ^ { 4 } x + \cos ^ { 6 } x + \sin ^ { 6 } x = 2$$ in the interval $[ 0,2 \pi ]$ is
Let $-\frac{\pi}{6} < \theta < -\frac{\pi}{12}$. Suppose $\alpha_1$ and $\beta_1$ are the roots of the equation $x^2 - 2x\sec\theta + 1 = 0$ and $\alpha_2$ and $\beta_2$ are the roots of the equation $x^2 + 2x\tan\theta - 1 = 0$. If $\alpha_1 > \beta_1$ and $\alpha_2 > \beta_2$, then $\alpha_1 + \beta_2$ equals
(A) $2(\sec\theta - \tan\theta)$
(B) $2\sec\theta$
(C) $-2\tan\theta$
(D) $0$
Let $S = \left\{x \in (-\pi, \pi) : x \neq 0, \pm\frac{\pi}{2}\right\}$. The sum of all distinct solutions of the equation $\sqrt{3}\sec x + \operatorname{cosec} x + 2(\tan x - \cot x) = 0$ in the set $S$ is equal to
(A) $-\frac{7\pi}{9}$
(B) $-\frac{2\pi}{9}$
(C) $0$
(D) $\frac{5\pi}{9}$
Let $a , b , c$ be three non-zero real numbers such that the equation $$\sqrt { 3 } a \cos x + 2 b \sin x = c , x \in \left[ - \frac { \pi } { 2 } , \frac { \pi } { 2 } \right]$$ has two distinct real roots $\alpha$ and $\beta$ with $\alpha + \beta = \frac { \pi } { 3 }$. Then, the value of $\frac { b } { a }$ is $\_\_\_\_$.