NCERT Class 12 · Ch 6 Exercise 6.1 · Q1
NCERT Class 12 Maths · Chapter 6 Applications Of Derivatives · Exercise 6.1 Question 1
Find dA/dr for a circle at (a) r=3 cm, (b) r=4 cm.
💡 Concept Hints
- Identify the domain and the inner and outer functions, or the relevant one-sided limits.
- Apply the appropriate differentiation or limit rule, keep all chain factors, and check exceptional points.
✅ Step-by-Step Solution
Final Answer: (a) 6π cm; (b) 8π cm.
- A=πr², so differentiating with respect to r gives dA/dr=2πr.
- Substitute r=3 and r=4 to obtain 6π and 8π cm²/cm, respectively.
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