secondary 2 chevron_right Maths

Trigonometry Question:
When the top T of a mountain is viewed from point A, 2000m from the ground, the angle of depression 'a' is equal to 15 degrees and when it is viewed from point Blank on the ground the angle of elevation 'b' is equal to 10 degrees. If points A and B are on the same vertical line, find the height of the mountain. (Round the answer off to one decimal place.)

The diagram is in the picture attached.
In the diagram:
h=height of the mountain.