OCR MEI Paper 1 2022 June — Question 10

Exam BoardOCR MEI
ModulePaper 1 (Paper 1)
Year2022
SessionJune
TopicConnected Rates of Change

10 A triangle ABC is made from two thin rods hinged together at A and a piece of elastic which joins \(B\) and \(C\). \(A B\) is a 30 cm rod and \(A C\) is a 15 cm rod. The angle \(B A C\) is \(\theta\) radians as shown in the diagram. The angle \(\theta\) increases at a rate of 0.1 radians per second.
Determine the rate of change of the length BC when \(\theta = \frac { 1 } { 3 } \pi\).