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MathsMediumMCQ2016 · 10 Apr Online

Q82.Let f(x) = sin4x + cos4x. Then, f is an increasing function in the interval: (1) ] 5π8 , 3π4 [ (2) ] π2 , 5π8 [ (3) ] π4 , π2 [ (4) ]0, π4 [

What This Question Tests

The problem tests the ability to find the derivative of a trigonometric function and use its sign to determine the intervals where the function is increasing.

Concepts Tested

Derivative for monotonicityTrigonometric identities

Formulas Used

f'(x) > 0 for increasing function

sin²x + cos²x = 1

sin(2x) = 2sinxcosx

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