A rectangle has length l = 2t + 3 cm and breadth b = t + 1 cm. Find dA/dt at t = 2 s.
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A rectangle has length l = 2t + 3 cm and breadth b = t + 1 cm. Find dA/dt at t = 2 s.

G1 Physics · Accepted Answer

A=lb. At t=2: l=7 cm, b=3 cm, dl/dt=2 cm s⁻¹, db/dt=1 cm s⁻¹. Using product rule: dA/dt=l(db/dt)+b(dl/dt) =7(1)+3(2)=13 cm² s⁻¹.