A tower's shadow is 40 m longer when the Sun's altitude is 30 degrees than when it is 60 degrees. The tower is:

1. Set up tangents at both angles with the same height. 2. Solving gives three x equal to x plus forty. 3. So the height is 20 root 3 m. _Source: syllabus Mathematics Class X, Chapter 9, Some Applications of Trigonometry._