Trigonometry
This question is about Trigonometry
Transcript
00:00First of all, we will align some statements, what you have to know, you can label it in any way, this can be A, B, this point can be C, and this is D.
00:15We have to know the distance between the tree and the building, so basically you have to know AB, that is the distance between the tree and the building.
00:25And you have to know the height of the building, that is BD, the height of the building.
00:32How tall is the building?
00:35We have to know these two things in this question.
00:38We have represented the height of the building with BD.
00:43Now, we have this triangle OBA, we will take this and apply tan on it.
00:52Why? Through proper brush.
00:55With tan, you will get perpendicular and base.
00:59So, very easy question.
01:01First, we will mention our triangle OAB.
01:07You know tan theta is perpendicular over base.
01:17The height perpendicular to base is 12 meters.
01:21Base is AB.
01:25Tan 45 degrees is equal to 1.
01:27Therefore, this question will become easier.
01:32Simply, you will get the answer AB which is 12 meters.
01:37That means the distance between the tree and the building is 12 meters.
01:43Now, we will come to the height.
01:45To find the height, we will calculate this small triangle OCD.
01:52Why?
01:53Because we have to know what is missing in this triangle.
01:57We have to know CD.
02:00Now, you will take this triangle.
02:09You will use tan.
02:11You will get perpendicular and base.
02:15If AB is 12 meters,
02:21I have just extended this triangle.
02:23This is not a different thing.
02:25If this is 12 meters, this will also be 12 meters.
02:28Now, you have base and angle.
02:32You just have to find perpendicular.
02:34Again, we will use tan.
02:36Because tan theta is perpendicular.
02:41To find anything, two things should be there and one thing should be missing.
02:47So, it will be tan 30 degrees.
02:52We do not know perpendicular.
02:54This is CD and base is 12.
02:57If we calculate tan 30 degrees, it will be 0.57.
03:03Simply, you multiply 12 by this.
03:06You will get CD.
03:10That is 6.84 meters.
03:14Now, what do we need?
03:16We need height of the building.
03:18If this is 12, this is also 12.
03:21When you add 6.84 in 12, you will get the answer.
03:27So, height of the building is BD.
03:32How did we get BD?
03:34When we add CD in BC.
03:37That is 12 plus 6.84.
03:41What will be this?
03:43It will be 18.84.
03:48Now, BD will be equal to BC plus CD.
03:55This is 12.
03:57This is 6.84.
03:59Both will be equal to 18.84.