Evaluate the following limits:
$\lim _{x \rightarrow 0} \frac{\cot 2 x-\operatorname{cosec} 2 x}{x}$
To Find: Limits
NOTE: First Check the form of imit. Used this method if the limit is satisfying any one from 7 indeterminate form.
In this Case, indeterminate Form are $\infty \times \infty$
$\operatorname{cosec} 2 x-\cot 2 x=(1-\cos 2 x) / \sin 2 x$
$\lim _{x \rightarrow 0} \frac{\cot 2 x-\operatorname{cosec} 2 x}{x}=\lim _{x \rightarrow 0} \frac{\cos 2 x-1}{x \sin 2 x}=\lim _{x \rightarrow 0} \frac{\frac{\cos 2 x-1}{x^{2}}}{\frac{x \sin 2 x}{x^{2}}}=\lim _{x \rightarrow 0} \frac{\frac{4[\cos 2 x-1]}{(2 x)^{2}}}{\frac{2 \sin 2 x}{2 x}}$
Formula used: $\lim _{x \rightarrow 0} \frac{1-\cos x}{x^{2}}=1 / 2$ and $\lim _{x \rightarrow 0} \frac{\sin x}{x}=1$
$\lim _{x \rightarrow 0} \frac{\cot 2 x-\operatorname{cosec} 2 x}{x}=\lim _{x \rightarrow 0} \frac{\frac{4[\cos 2 x-1]}{(2 x)^{2}}}{\frac{2 \sin 2 x}{2 x}}=\frac{-4}{2}=-2$
Therefore, $\lim _{x \rightarrow 0} \frac{\cot 2 x-\operatorname{cosec} 2 x}{x}=-2$
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All Study Material
- JEE Main
- Exam Pattern
- Previous Year Papers
- PYQ Chapterwise
- Physics
- Kinematics 1D
- Kinemetics 2D
- Friction
- Work, Power, Energy
- Centre of Mass and Collision
- Rotational Dynamics
- Gravitation
- Calorimetry
- Elasticity
- Thermal Expansion
- Heat Transfer
- Kinetic Theory of Gases
- Thermodynamics
- Simple Harmonic Motion
- Wave on String
- Sound waves
- Fluid Mechanics
- Electrostatics
- Current Electricity
- Capacitor
- Magnetism and Matter
- Electromagnetic Induction
- Atomic Structure
- Dual Nature of Matter
- Nuclear Physics
- Radioactivity
- Semiconductors
- Communication System
- Error in Measurement & instruments
- Alternating Current
- Electromagnetic Waves
- Wave Optics
- X-Rays
- All Subjects
- Physics
- Motion in a Plane
- Law of Motion
- Work, Energy and Power
- Systems of Particles and Rotational Motion
- Gravitation
- Mechanical Properties of Solids
- Mechanical Properties of Fluids
- Thermal Properties of matter
- Thermodynamics
- Kinetic Theory
- Oscillations
- Waves
- Electric Charge and Fields
- Electrostatic Potential and Capacitance
- Current Electricity
- Thermoelectric Effects of Electric Current
- Heating Effects of Electric Current
- Moving Charges and Magnetism
- Magnetism and Matter
- Electromagnetic Induction
- Alternating Current
- Electromagnetic Wave
- Ray Optics and Optical Instruments
- Wave Optics
- Dual Nature of Radiation and Matter
- Atoms
- Nuclei
- Semiconductor Electronics: Materials, Devices and Simple Circuits.
- Chemical Effects of Electric Current,