From a boat, the angle of elevation of the top of a vertical cliff is 35°…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
From a boat, the angle of elevation of the top of a vertical cliff is .
- What is the angle of depression of the boat, seen from the top of the cliff?
- What angle does the line of sight make with the cliff face at the top?
Need a reminder? The key ideaShow
The line of sight joins the eye to the object. The angle of elevation (looking up) and the angle of depression (looking down) are measured from the horizontal. For one line of sight they are equal, because they are alternate angles between parallel horizontals.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) The angle of depression equals the angle of elevation, because they are alternate angles. It is .
Step 2. (b) The triangle has a right angle at the foot of the cliff and at the boat. The angle at the top is .
Answer: (a) ; (b) .
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