P is the position of the kite. Its height from the point Q (on the ground)= PQ = 60m.

Let OP= l be the length of the string.

$$\angle P O Q = 60^{\circ}$$ $$sin\Theta = \frac{Opposite}{Hypotenuse}$$ $$\frac{PQ}{OP} = sin 60^{\circ}$$ $$\frac{60}{L} = sin 60^{\circ} = \frac{\sqrt{3}}{2}$$ $$\frac{60}{L} = \frac{\sqrt{3}}{2}$$ $$L = \frac{3 * 2 * 20}{\sqrt{3}}m$$ $$L = 40\sqrt{3}m$$

Therefore, the length of the string is $$40\sqrt{3}m$$.

Explore more such questions and answers at BYJU’S.