Question

A point is directly below a window. Another point B is 15 m from A and at the same horizontal level. From B angle elevation of the top of the bottom of the window is 30° and the angle elevation of the top of the widow is 35°. Calculate the vertical distance

Answer 1

If you want the vertical distance from point A to the bottom of the window you would use the right angled triangle produced by your sketch and find the height using the tangent ratio.
Tan theta = opposite / adjacent
tan30=height/15

Now... if you were actually looking for the distance from the bottom of the window to the top of the window.... it would take a bit more work.
step 1) find the height from A to the bottom of the window (as done above
step 2) use the Pythagorean theorem to find the distance from the bottom of the window to point B
step 3) use the Pythagorean theorem to find the distance from the point B to the top of the window...
step 4) now you have a side angle side triangle and you can use the cosine law to find the distance from the bottom to the top of the window : )

Again... your description in the question was a bit vague and I wasn't sure which distance you were required to find. I would say that if you have already studied the COSINE LAW then it would be the second solution with steps 1-4

Answer 2

An answer