In this paragraph we learn how to use the ratio height:distance to calculate the angle of elevation. The result of the division is called the gradient or tangent of ∠A. This is written as tan ∠A.
The book doesn't teach you the angle of depression, but it is still something you need to learn. The picture below shows you the difference between the two. If the object is higher than the angle, it is called the angle of elevation. If the object is lower than the angle, it is called the angle of depression
Like we said before, the result of the division is called the gradient or tangent of ∠A. This is written as tan ∠A.
Remember to always make a sketch and write down the information that you have!
The picture below will give you a different explanation for calculating the angle of elevation or depression which can be insightful for those who need it.