"If the angle of elevation of Sun increases from $0^o$ to ${90}^o$, then the length of shadow of a tower decreases." Is this statement true? Justify your answer.

As angle of elevation of sun increases till ${90}^0$ from $0^0$, the length of shadow decreases.

 The length of shadow of tower will be given by distance between bottom of tower to the point where sunlight ray hits the ground which is coming from the top of the tower. That distance will become less as sun elevation angle increases.