A paper has the precise shape of a triangle which is denoted by ABC, with AB = BC = CA = x (say) and, D is a point on BC.

Vertex A is joined onto D forming the crease EF - where E is on AB and F is on AC.

Given that DF is perpendicular to BC, determine:

1. The length of EF in terms of x.
2. The area of each of the triangles BED, DEF and DFC in terms of x.

Geometer's Sketchpad approximates EF as 0.56841 x.

Area of BED ~= 0.11603 * x^2

Area of DEF ~= 0.12740 * x^2

Area of DFC ~= 0.06218 * x^2

Posted by Charlie on 2013-04-13 14:41:49