In a triangle $ABC$, $AB=5$ cm and $AC=4$ cm. If angle $BAC$ is decreasing at a constant rat

Question

In a triangle $ABC$, $AB=5$ cm and $AC=4$ cm. If angle $BAC$ is decreasing at a constant rate of $0.2$ radians per second, find the rate of change of the length $BC$ at the instant where $\angle BAC=\frac{\pi }{3}$ radians, giving your answer in centimetres per second to $3$ significant figures. [5]

Accepted Answer

$0.756 $ cm/s

2024 EJC Promo Q4

2024 EJC Promo Q4

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