Review question

# An exact value for $\sin 15^{\circ}$... Add to your resource collection Remove from your resource collection Add notes to this resource View your notes for this resource

Ref: R7050

## Suggestion

1. Without using tables, show for $\theta=15^\circ$ that $\sin\theta=\dfrac{\sqrt{6}-\sqrt{2}}{4}$, and find the values of $\cos\theta$ and $\tan\theta$.

For what angles do we know the exact values of $\sin\theta$?

What trigonometric formulae might be useful here? How about expanding $\sin(a-b)$, choosing $a$ and $b$ carefully?