[tex]tan80 = \frac{d}{30}[/tex]
Recall all of the trigonometric properties (SOH CAH TOA)
Your angle of interest is 80° so you'd have to find a relationship between d and the angle of interest.
You know it's a right angle triangle because it's the perpendicular distance (height) to the ground, and it always forms a right triangle.
The tangent function does not need to worry about the hypotenuse, so you'd instinctively use the tangent function. Tangent function is opposite/adjacent, so [tex]tan80 = \frac{d}{30}[/tex]
