If you increase on every row, it makes a triangle from the bottom tip to the top edge. One inc every other row would have one side increasing but the other would be straight. So if you got to a certain size and decreased on the same edge you increased, it would make a triangle from side tip to side tip. If you increased 2 on every other row, one on each edge, it also makes a triangle from the bottom tip to the straight top edge.
sue- knitting heretic