I'd do it the old fashioned way with a rod. No calculating involved.
Draw it up on a board.
Make the 5 points as @niall Y suggested- solid or joined boards. Angles not critical as long as they are identical.
Lay them on the rod and take off marks for the vertical cuts where the arms join. Cut along the lines.
You could make the points first by eye, then draw them on the rod for the vertical cuts etc