NIMCET 2023 — Mathematics PYQ
NIMCET | Mathematics | 2023Number of point of which f(x) is not differentiable in

Number of point of which f(x) is not differentiable in
A modulus function of the form is generally non-differentiable at points where , provided at those points. These points create sharp corners ("v-shapes") on the graph.
For our function, we set the inner expression to zero:
We need to find the values of where within the closed interval :
In the positive domain , at .
In the negative domain , at .
Thus, the critical points to check are:
Let's check the differentiability at using left-hand and right-hand derivatives.
Near :
For x < \frac{\pi}{2} (First Quadrant), \cos x > 0 \implies f(x) = \cos x + 3.
For x > \frac{\pi}{2} (Second Quadrant), \cos x < 0 \implies f(x) = -\cos x + 3.
Since the Left-Hand Derivative () Right-Hand Derivative (), a sharp turn exists at , making it non-differentiable.
By symmetry, the function is also non-differentiable at (where the left-hand derivative is and the right-hand derivative is ).
There are exactly 2 points ( and ) in the interval where the function is not differentiable.
The correct option is A) 2.