Tangent Law

The height of the tree is calculated with the help of the tangents of the angles to the top and base of the tree and the distance of the observer from the tree.

Simple example is of standing tree in plane ground

BD = AE+ ED Tan α

In case of sloping ground

BE = FD + DE = AD (Tan A + Tan B)

Sine Law

In trigonometry, in any triangle, sines of angles are proportional to the opposite sides. Thus,