Question

Two small fires are spotted by a ranger from a fire tower 60 feet above ground. The angles of depressions re 11.6° and 9.4°. How far apart are the fires? (The fires are in the same general direction from the tower.)

Answer 1

The two fires are about 70 feet from each other. The assumption is that the ground is relatively level and that a right triangle will be made with the three points of the triangle being the ranger, the spot on the ground directly beneath the ranger, and the fire itself. So the distance to the first fire will be: Calculate the angle. That will be 90° - 11.6° = 78.4° The distance will be tan(78.4) = X/60 60 tan(78.4) = X 60 * 4.871620136 = X 292.2972082 = X And that's how far the 1st fire is from the ranger's station. Now for the 2nd angle = 90° - 9.4° = 80.6° 60 tan(80.6) = X 60 * 6.040510327 = X 362.4306196 = X And the distance between the two fires will be the difference in distance from the tower, so 362.4306196 - 292.2972082 = 70.13341146 Rounding to 2 significant figures gives 70 feet.