How many edges in a triangular based pyramid?

Answer 1

Six - a pyramidic form with a triangular base is going to have three edges along the periphery of the base. There will be three planar surfaces that comprise the "upright" side surfaces, each of which will also be triangular in shape and sharing common edges with those triangular surfaces on either side. Visualize it by drawing an equilateral triangle on a sheet of paper. Next, bisect each interior angle of that triangle, stopping each bisector where it intersects with the other bisectors. Now count the line segments that extend from apex to apex and add to that number the line segments that extend from an apex to the bisector intersection. Total count is six line segments... thus six edges.