Quote:
Originally Posted by Gavin1234
So looks like my primary school geometry teachers were right along when they said one day I might need to use a protractor.
I’ve had to move my scope further from my house a few meters to get a better view of objects early in the morning. I had previously marked out the spots for my tripod legs and got really good alignment very easily by using those. It was point straight at true south.
Trying to setup the same way in my new spot and I’ve run into a problem. I’ve got an iPhone 7, 8 and iPhone X, a galaxy s6 and a brand new iPad Pro and all of the compasses don’t work. They all give me different lines and none match the original line that works.
I’ve drawn out a line for the original spot and basically I want to draw another line about two meters away that is exactly parallel to it so they are both pointing to true south.
How do I make sure they are both parallel? Too big for a compas and if I just measure the difference between the two at regular intervals how do I make sure the tape measure is at the right angle. Do I have to go get a protractor?
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I've been thinking the same in preparation for installing new wheels on the underside of my observatory roof..... Pythagoras is your friend.
Take the line you have. Measure it. Call this x.
If you want another line 2m away, exactly parallel, draw out two right angle triangles from the ends of the line, using your line as one side, and the 2m spacing as the other. The length of the diagonal (hypotenuse) will be the square root of (x^2 + 4). Ie if your current line (x) is 4m long, the diagonal distance will be 4.47m. Find the point from each end of your line where arcs of length 2m and 4.47m meet (for a 4m line) - this is the ends of your new parallel line.
Remember the 3-4-5 triangle.... that's one special case you can use too.....