## Trigonometry 7th Edition

$120^{\circ}$
Hour hand completes one rotation in 12 hours, thus rotates through $360^{\circ}$- i.e. degrees swept in 12 hours = $360^{\circ}$ Therefore degrees swept in 1 hour = $\frac{360}{12}$ = $30^{\circ}$ So degrees swept in 4 hours = $4 \times 30^{\circ}$ = $120^{\circ}$