1st two grids are 90 to each other. The last grid intersects the middle of the square the other 2 form ie going right through the middle of a square box (for circle center?) Unfortunately, the scale on the chart is not 1/1 it's 1.5/1 so 45 on a square chart is 33.69 on this chart. The Gann
angle tool didn't work for me because of this.