# Folding Aeroplane (HKCEE 1999 )

- Author:
- Anthony OR 柯志明

- Topic:
- Triangles, Trigonometry

In the figure, ABC is an equilateral triangle of side 24 cm and BD = DE = EF = FC. It is folded to form an aeroplane by dragging the red point so that D and F coincide. The aeroplane is supported by two vertical sticks BM and CN so that A,B, D, F, C lie on the same plane.
(a) Find the distance between the tips, B and C, of the wings of the aeroplane.
(b) Find the inclination of the wings of the aeroplane to the horizontal ground.
(c) Find the length of the stick CN.