A ladder is placed against a vertical tower. If the ladder makes an angle of 30° with the ground and reaches upto a height of 15 m of the tower; find the length of the ladder.

AC is the ladder and BC is the tower.

In Δ ABC,

$\text{sin 30°} = \dfrac{Perpendicular}{Hypotenuse}\\[1em] ⇒ \dfrac{1}{2} = \dfrac{BC}{AC}\\[1em] ⇒ \dfrac{1}{2} = \dfrac{15}{AC}\\[1em] ⇒ AC = 15 \times 2\\[1em] ⇒ AC = 30$

Hence, length of the ladder = 30 m.