Verified Solution • 2025–26 Session moderate

QJEEM21Mab74e: JEE Main 2021 Mathematics - Class 12 JEEM21Mab74e Solution: Let be a function defined by f ( x ) = { max { sin ⁡ t : 0 ≤ t…

Let f:[0,∞)→[0,3]f:[0,\infty ) \to [0,3] be a function defined by

f(x)={max{sin⁡t:0≤t≤x},0≤x≤π2+cos⁡x,x>π

Then which of the following is true?

Multiple Choice Options

  • A f is continuous everywhere but not differentiable exactly at one point in (0, ∞\infty )
  • B f is differentiable everywhere in (0, ∞\infty )
  • C f is not continuous exactly at two points in (0, ∞\infty )
  • D f is continuous everywhere but not differentiable exactly at two points in (0, ∞\infty )

Step-by-Step Verified Solution

Graph of max⁡{sin⁡t:0≤t≤x}\max \{ \sin t:0 \le t \le x\} in x∈[0,π]x \in [0,\pi ]

JEE Main 2021 (Online) 27th July Evening Shift Mathematics - Limits, Continuity and Differentiability Question 112 English Explanation 1

& graph of cos x for x∈[π,∞)x \in [\pi ,\infty )

JEE Main 2021 (Online) 27th July Evening Shift Mathematics - Limits, Continuity and Differentiability Question 112 English Explanation 2

So graph of

f(x)={max{sin⁡t:0≤t≤x},0≤x≤π2+cos⁡x,x>π

JEE Main 2021 (Online) 27th July Evening Shift Mathematics - Limits, Continuity and Differentiability Question 112 English Explanation 3

f(x) is differentiable everywhere in (0, ∞\infty )

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