SOLUTION: Points A and B are on the same horizontal line with the foot of a hill and the angles of depression of these points from the top of the hill are 30.2° and 22.5°, respectively. I

Algebra ->  Trigonometry-basics -> SOLUTION: Points A and B are on the same horizontal line with the foot of a hill and the angles of depression of these points from the top of the hill are 30.2° and 22.5°, respectively. I      Log On


   



Question 1198352: Points A and B are on the same horizontal line with the foot of a hill and the angles of depression of these points from the top of the hill are 30.2° and 22.5°,
respectively. If the distance between A and B is 75.0m, what is the height of the hill?

Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

This is what the diagram would look like

Point C is the base of the hill, and D is the top of the hill.
Point E is to help set up the angles of depression (angle EDA = 22.5° in red; angle EDB = 30.2° in blue)

An angle of depression is where you start facing directly horizontal. Then you aim downward that amount of degrees to face the object.

Segments AC and ED are parallel as they are horizontal lines.
Using the alternate interior angle theorem, we have these two facts:
  • angle EDA = angle DAC = 22.5 degrees (red)
  • angle EDB = angle DBC = 30.2 degrees (blue)
This is an equivalent diagram where this time we're focusing on angles of elevation.

The reason why I'm doing this is to then bring your attention to these similar problems in the links below:
https://www.algebra.com/algebra/homework/Vectors/Vectors.faq.question.1198061.html
https://www.algebra.com/algebra/homework/Trigonometry-basics/Trigonometry-basics.faq.question.1198040.html
In those links I've used angles of elevation, and the distance between observation points, to determine the height of the tall object.

This hint should be a good enough start to get you going.
If you're still stuck, then please let me know.