Crane-jib extension and roof clearance

Crane-jib extension and roof clearance

Secondary 2
TGM Original Questions

A crane stands in a warehouse 22 m high. Its pivot \(A\) is 9 m above ground, and its jib \(AB=16\) m is inclined \(30^\circ\) above horizontal \(AC\). A vertical cable from \(B\) reaches ground at \(D\).

  1. Find \(BD\).
  2. The jib is extended by 4 m and raised by a further \(15^\circ\). Determine whether its tip will hit the roof. Give the new tip height and roof clearance to 2 decimal places.

Solution:

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Answer:(a) \(17\) m; (b) Yes; the calculated tip height is \(23.14\) m, exceeding the roof by \(1.14\) m.

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