1.8.6 Compound and double angle formulae (A-level only)

a.

By writing $\sin 3A\,$ as $sin⁡(2A+A)\sin(2A + A)$ , show that $sin 3A = 3\sin A - 4\sin^3 A$

[2]

b.

Solve, for $\leq A \leq \pi$ , the equation,

3\sin A - 4\sin^3 A = \frac{1}{\sqrt{2}}

Give your answers in terms of $π\pi$ .

[4]

a.

By writing $\sin 3A\,$ as $sin⁡(2A+A)\sin(2A + A)$ , show that $sin 3A = 3\sin A - 4\sin^3 A$

[2]

b.

Solve, for $\leq A \leq \pi$ , the equation,

3\sin A - 4\sin^3 A = \frac{1}{\sqrt{2}}

Give your answers in terms of $π\pi$ .

[4]

1.8.6 Compound and double angle formulae (A-level only) Questions