by Gyrotech » Wed May 08, 2013 10:43 am
There is a simple way to do that by using the mCircle method off the CAD interface. Here is what the manual says (I got this from the pdf version of the manual, emphasis is mine).
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Xc,Yc - Lon, Lat coordinates (in decimal degrees) of the center of the circle.
Xp,Yp - Lon, Lat coordinates of the first point on the circle circumference.
Note that if Xp=Xc then Yp-Yc is the radius of the circle in degrees, and if Yp=Yc, then Xp-Xc is the radius of the circle in degrees.
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All you need to do is remember to convert your radius from miles to degrees. And here is where it may be a bit tricky, because...
1 degree of latitude = about 69.11 miles
1 degree of longitude = about 69.11 miles along the equator. But all of the longitudes come together at the poles, so the farther you are from the equator, the fewer miles there are in one degree. So, number of miles in 1 degree of longitude = (69.11) x (cosine of the latitude) at that point. So, you could use the aspect ratio to adjust for that.