Answer:
sin (60° - 20)°
sin (40°)
Explanation:
Note that:
sin(A - B) = sinAcosB - cosAsinB
The given trigonometric expression is:
sin 60° cos 20° - cos 60° sin 20°
Applying the addition rule of trigonometry written above:
sin 60° cos 20° - cos 60° sin 20° = sin(60° - 20°)
This can also be written as sin (40°)
