How do you sketch 3 vertical planes that intersect in 1 line?
Wow! It's tough to answer a drawing question without showing you. The best way I know is to draw a straight vertical line first. That's your line of intersection.
Now mark a large "X" near the top of the vertical line. That's going to be 2 planes intersecting at this line. Use one color for one line segment of the X (let's say blue). Bring 2 vertical lines down from each endpoint the same distance (let's say 5 inches) and connect at the bottom. You now have a blue parallelogram representing one plane. Use a second color (red) for the other segment of the X. Bring 2 vertical lines down from the endpoints (agiain, 5 inches) and create a second, red, plane. The last plane is going to take a 3rd line segment through the X at the top (a third color - purple) on a different angle. Bring the 2 vertical purple lines from the endpoints & join into the parallelogram.
What you should have is 3 colored planes (you could lightly shade each plane) and they all meet at the first vertical line.