A tip about triangles: if the method you use to make a triangle leaves you with a center point, or if you ask for one (Attributes pallette), this center point is NOT the center of the triangle, but the center of an imaginary bounding box that the triangle would fit into completely. If you rotate the triangle on this center, you'll get a lopsided rotation. Draw a circle that touches the inside of the triangle on all three sides; the center of the circle is the "true" center of the triangle.
For the longest time I thought this was a bug; a teacher my employer hired set us straight.