Height of a tower
From a point P on level ground, the angle of elevation of the top of a tower is 26 °50.' From a point 25meters closer to the tower and on the same line with P and the base of the tower, the angle of elevation of the top is 53°30.' Approximate the height of the tower.
tan 26°50'=height (OPPOSITE)
Generalize to the case where the first angle is alpha, the second angle is beta, and the distance between the two points is d. Express the height h of the tower in terms of d, alpha and beta.
ά=tan inverse htx