this diagram is no trick.
Draw a horizontal line: the water
draw a vertical line: the lighthouse.
Where the vertical line hits the water, call that point B: bottom of tower
At the top, label it T.
The height of the vertical line is 25
Now somewhere out on the water, label a point S: sailboat.
The line TS makes a 12° angle with the water. (No, it doesn't have to really be 12° -- just label it that way.
Now, the distance BS (from the boat to the base of the lighthouse) can be found using
25/BS = tan 12°
now, was that so hard? All you have to do is take one piece of information at a time, and use it as described.
The light on the Prince Shoal lighthouse is 25m above water level. From a position behind the light, the angle of the depression of the sailboat is 12 degrees. How far is the sailboat from the lighthouse, to the nearest metre?
(I have no idea how the diagram would look - it uses the primary trigonometry ratios to solve for the distance)
1 answer
1 answer