Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

(a)[6]

Express $3\sin 2\theta \sec \theta + 10\cos(\theta - 30^\circ)$ in the form $R \sin(\theta + \alpha)$, with $R > 0$ and $0^\circ < \alpha < 90^\circ$. State the value of $\alpha$ correct to 2 decimal places.

(b)[3]

Hence solve $3\sin 4\beta \,\sec 2\beta + 10\cos(2\beta - 30^\circ) = 2$ for $0^\circ < \beta < 90^\circ$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Use $\sin 2\theta = 2\sin\theta\cos\theta$ and $\sec\theta = \dfrac1{\cos\theta}$ to show that $6\sin\theta$ is obtained

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI