(a)

A state trooper is hidden from a highway.

One second after a truck passes, the angle between the highway and the line of observation from the patrol car to the truck is measured.

If , how fast is the truck traveling :

Since the angle and the opposite side is knowm, the unknown one is adjacent side.

Let the adjacent side be .

Therefore, use the function.

.

Therefore, speed is .

Convert into .

(b)

If , how fast is the truck traveling :

Since the angle and the opposite side is knowm, the unknown one is adjacent side.

Let the adjacent side be .

Therefore use the function.

.

Therefore, speed is .

Convert into .

(c)

The trooper willissue a ticket with a speed limit is or more.

Now convert into .

.

(a)

or .

(b)

or .

(c)

The angle must be below .