The shadow of Qutab Minar is 81 m long when the angle of elevation of the Sun is θ. Find the height of the Qutab Minar if tanθ= 0.89.

Drawing a diagram of the given condition,

Using a diagram to explain why angle BCA is used as the angle of elevation.

In the diagram θ is the angle of elevation of point C with respect to point A where AB is the reference line from which the angle is measured.

From the theory explained above it easily understood that angle SCD is the angle of elevation

But from the diagram is also seen that angle SCD= angle ACB as both represent the same angle.

height of qutab minar = 0.89 × shadow of qutab minar

height of qutab minar= 0.89 × 81

Therefore, the height of the qutab minar is 72.09 m.