
Re: Geometry #24
Posted:
Jun 19, 2013 3:26 PM



If you place the smaller triangle in the larger triangle,with <A mapping onto <D, you see that AB is half of DE and AC is half of DF. When midpoints of a triangle are joined, the segments are parallel. Therefore, <ACB and <DFE are congruent corresponding angles. This gives two triangles similar by using AA. Likewise, when a segment joins the midpoints of two sides of a triangle, it is half the third side. Therefore, all corresponding sides are in the ratio 1:2 and the triangles can be proven similar by SSS. **See attached file

