draw one angle vertically down (vertex, or tip of the andgle, on top and the sides spreading in two directions down like someone standing with the legs spread, draw the other angle horizontal, the vertex to the far left and the sides spreading and crossing the those of the vertical one). there will be 4 points of contact 

now to get three points of contact, slide the horizontal angle to the right side just enough such the vertex is at the left leg of the vertical angle( that's one point of contact) the sides of the horizontal angle will cross those of the vertial one at two points. That's three common points