Better! I have to point out, though: three legs separated by right angles do not form a triangle, they form an open quadrilateral. This experimental setup will show different results on a flat earth than on a round earth. On a flat earth, if you connect the dots from your starting position to your end, the missing leg of the four sided figure will be exactly 3km long, precisely perpendicular to sides 1 and 3, and parallel to side 2. The figure will be a perfect square. On a round earth, however, the missing side will be less than 3km, and not perpendicular or parallel to any of the previous sides. This is because on the round surface, the third leg is not parallel to the first leg along its entire length. This is easiest to see in the extreme, where each leg is a significant way around the world. Let's start at the Arctic Circle, near (but not AT) the North Pole, and go south a little less than 1/4 of the way around the world, so you end up at the equator. Turn left 90 degrees to face east, and go the same distance. Still at the equator. Turn left 90 degrees to face north, and go the same distance. You're back at the Arctic Circle, some small distance east of your starting point. The fourth side of the quadrilateral is quite a bit smaller than the other three sides. The same result, but much smaller, will be obtained if you can accurately produce straight 3km legs on a round earth and accurately measure the distance of the final leg. I don't know what the difference would be, it may be too small to be detected by amatuer level equipment, but a surveyor would be able to measure it.