00:01
So the best way to approach this problem is to go ahead and draw a diagram.
00:04
So we have told that we have a ladder that's leaning against the building.
00:07
So let's say that this is the ground.
00:09
Here's our building.
00:11
And we have this ladder that's leaning against it.
00:13
So anytime they give you this, you assume that the building is going to form a 90 -degree angle with the ground.
00:19
Now we're told that the ladder is 20 feet.
00:21
So in this right triangle, that would be the length of our hypotenuse.
00:24
Now, we're told that the base of the ladder is six feet from the base of the building.
00:28
So here's the base of the building, here's the base of the ladder, so the distance between them is equal to 6 feet.
00:34
Now we're also told, or what we're writing as to find, is the angle of elevation of the ladder.
00:40
Well, the angle of elevation would be the angle that the ladder makes with the ground.
00:43
So that would be this angle right here.
00:45
Well, compared to this angle x, we're given the adjacent side and the hypotenuse.
00:50
So we're going to use our cosine function.
00:52
So if the cosine of angle x equal to the adjacent side 6 divided by the hypotenuse, which is 20.
00:58
So to solve for x, what we need to do is take the inverse cosine of 6 divided by 20...