Let's begin by identifying the information given to us:
BC = 14, AC = x
Angle B = 72°
We have one known side, one known angle & one unknown side. As such, we will use Trigonometric Ratio (SOHCAHTOA)
tan 72° = opposite/adjacent
tan 72° = x/14
x = 14 × tan 72°
x = -3.67 ≈ -3.7
