Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

From the diagram, triangle $ABC$ is right-angled at $C$, and $M$ is the midpoint of $BC$. You are told that angle $ABC = \frac{\pi}{3}$ radians and angle $BAM = \theta$ radians. If the lengths of $BM$ and $MC$ are each called $x$,
(a)[3]

find $AM$ expressed in terms of $x$.

(b)[2]

show that the angle is $\theta = \frac{\pi}{6} - \tan^{-1}\left(\frac{1}{2\sqrt{3}}\right)$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct application of a trigonometric ratio, for example $\tan\left(\frac{\pi}{3}\right)=\frac{AC}{2x}$

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