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interesting integration:- integration of [0 to 90 deg] (sin x -cos x)/(1 - sin 2x)^0.5 dx?

the answer is coming zero by using properties of definite integrals, but it is coming 90 deg without using prop.

which answer is correct?

what do i do if a similar que comes in an exam?

Update:

PLEASE READ THE FULL QUE. AND TRY IT USING PROPERTIES OF DEFINITE INTEGRAL!

THEN THE ANSWER IS COMING ZERO!!

WHY SO?

2 Answers

Relevance
  • 7 years ago

    Note that numerator and denominator in this expression are same.

    1- sin 2x = sin2x+ cos2 x - 2 sin x cos x = (sin x-cos x)^2

    There fore rest of the operations are straight forward and answer is 90 degrees or pi/2 radians.

  • 7 years ago

    int (sinx -cosx)/(1-sin2x)^1/2

    = intsinx - cosx/(sin^2x+ cos^2x-2 sinx cosx)^1/2

    = int (sinx -cosx)/( sinx- cosx) dx

    = x lim 0 to pi/2

    = pi/2 answer

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