Practicing Success
Two ships are sailing in the sea on the two sides of a lighthouse. The angle of elevation of the top of the lighthouse is observed from the ships are 30º and 45º respectively. If the lighthouse is 90 m high, the distance (in m) between the two ships is? |
90(\(\sqrt {3}\) + 1) m 200(\(\sqrt {3}\) + 1) m 45(\(\sqrt {3}\) + 1) m 100(\(\sqrt {3}\) + 1) m |
90(\(\sqrt {3}\) + 1) m |
In ΔABC; tan 45° = 1 : 1 (AB) : (BC) ↓ ↓ 90m (90 m) AB = height of lighthouse = 90 m In ΔABD; tan 30° = 1 : \(\sqrt {3}\) (AB) : (BD) ↓ ↓ 90 90 × \(\sqrt {3}\) = 90\(\sqrt {3}\) distance between ships = DB + BC = 90\(\sqrt {3}\) + 90 = 90(\(\sqrt {3}\) + 1) m |