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CBSE Class 12 Mathematics 2026 Supplementary Paper 65(B)/7 · Q222 Marksrelated_rates

CBSE Class 12 Mathematics 2026 Supplementary Paper 65(B)/7 · Question 22 (Applications Of Derivatives)

The side of an equilateral triangle grows at 3 cm/s. Find its area rate when the side is 10 cm.

✅ Step-by-Step Solution

Final Answer: 15√3 cm²/s.
  1. Use A=√3 s²/4.
  2. Differentiate: dA/dt=(√3/2)s ds/dt.
  3. Substitute s=10 and ds/dt=3.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] Use A=√3 s²/4.
  • [1 mark] Differentiate: dA/dt=(√3/2)s ds/dt.
  • [0.5 marks] Substitute s=10 and ds/dt=3.

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All Questions in CBSE Class 12 Mathematics 2026 Supplementary Paper 65(B)/7

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