Answer :

Let f(x) = sin x + cos x,

f’(x) = cosx - sinx


Now, f’(x) = 0


cosx - sinx = 0


cosx = sinx


tanx = 1



Now,


If f’’(x) will be negative when (sinx + cosx) > 0, means both sinx and cosx are positive.


And, we know that sinx and cosx both are positive in the first quadrant.


Then, f’’(x) will be negative when


f’’(x) = -sinx – cosx = -(sinx + cosx)


Now, let us take x =



Then, by second derivative test,


f will be maximum at x =


And, the maximum value of f is



Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

If the sum of theMathematics - Board Papers

A metal box with Mathematics - Board Papers

Show that aRD Sharma - Volume 1

Find the local maMathematics - Board Papers

Prove that the seMathematics - Board Papers

Prove that the raMathematics - Board Papers

Prove that the leMathematics - Board Papers