Originally Posted by
rusty1363 yes there is a picture but ill write the text verbatim: At a time when the earth was 93,000,000 miles from the sun, you observe through a tinted glass that the diameter of the sun occupied an arc of 31'. Determine to the nearest ten thousand miles the diameter of the sun. Hint: Because the radius of arc AB is large and the central angle is small, the length of the diamater of the sun is approx. the length of the arc AB.
So the central angle is measured from the earth from the two radii that form the arc AB (the diameter of the sun).