Question:

Evaluate: $\int\frac{sin \,2x}{sin\left(x -\frac{\pi}{3}\right) sin\left(x+\frac{\pi}{3}\right)} dx $

Updated On: Jul 6, 2022
  • $log\left|sin\left(x+\frac{\pi }{3}\right) \right|-log \left|sin\left(x-\frac{\pi }{3}\right) \right| + C $
  • $log\left|sin\left(x+\frac{\pi }{3}\right) \right|+log \left|sin\left(x-\frac{\pi }{3}\right) \right| + C $
  • $log\left|sin\left(x-\frac{\pi }{3}\right) \right|-log \left|sin\left(x+\frac{\pi }{3}\right) \right| + C $
  • None of these
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The Correct Option is B

Solution and Explanation

Let $ I = \int\frac{sin\, 2x}{sin\left(x -\frac{\pi}{3}\right) sin\left(x+\frac{\pi}{3}\right)} dx $. then, $I = \int\frac{sin\left\{\left(x-\frac{\pi}{3}\right) + \left(x+\frac{\pi }{3}\right)\right\}}{sin\left(x-\frac{\pi }{3}\right) sin \left(x+\frac{\pi }{3}\right)} dx$ $\Rightarrow I = \int \frac{\left\{sin\left(x-\frac{\pi }{3}\right) cos \left(x+\frac{\pi }{3}\right) + cos\left(x-\frac{\pi }{3}\right) sin\left(x+\frac{\pi }{3}\right)\right\}}{sin\left(x-\frac{\pi }{3}\right) sin\left(x+\frac{\pi }{3}\right)} dx $ $\Rightarrow I=\int\left\{cot\left(x+\frac{\pi }{3}\right)+ cot\left(x-\frac{\pi }{3}\right)\right\}dx$ $\Rightarrow I = log\left|sin\left(x+\frac{\pi \:}{3}\right)\:\right|+log\:\left|sin\left(x-\frac{\pi \:}{3}\right)\:\right|\:+\:C$
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Concepts Used:

Integral

The representation of the area of a region under a curve is called to be as integral. The actual value of an integral can be acquired (approximately) by drawing rectangles.

  • The definite integral of a function can be shown as the area of the region bounded by its graph of the given function between two points in the line.
  • The area of a region is found by splitting it into thin vertical rectangles and applying the lower and the upper limits, the area of the region is summarized.
  • An integral of a function over an interval on which the integral is described.

Also, F(x) is known to be a Newton-Leibnitz integral or antiderivative or primitive of a function f(x) on an interval I.

F'(x) = f(x)

For every value of x = I.

Types of Integrals:

Integral calculus helps to resolve two major types of problems:

  1. The problem of getting a function if its derivative is given.
  2. The problem of getting the area bounded by the graph of a function under given situations.