Confusing Trigonometry Problem Lets say at an intersection the words "STOP HERE" are painted on the road in red letters 2.5m high. It is important that drivers using this lane can read the letters. How can I find the angle subtended by the letters to the eyes of a driver 20m from the base of the letters and 1.25m above the road? 
Is it right to use tan, so tanθ=1.25/20? Or am I missing something?

As others have said, the first step is to draw a  picture.  The driver's eye is at the top of the 1.25, and the letters cover the thick 2.5 along the bottom.  The angle to the bottom of the "Stop Here" is $\theta = \arctan \frac {20}{1.25}$ and the angle to the top of the "Stop Here" is $\arctan \frac {22.5}{1.25}$, so the angle subtended by the letters at the driver's eye is $\arctan \frac {22.5}{1.25}-\arctan \frac {20}{1.25}=\arctan 18-\arctan 16 \approx 86.82^\circ - 86.42^\circ \approx 0.40^\circ$
