Use the formula for secants in a circle. The formula for us in our situation is [tex]x^2=239,000(239,000+8,000)[/tex]. Work within the parenthesis first to get [tex]x^2=239,000(247,000)[/tex]. Do the multiplication now to get [tex]x^2=5.9033*10^{10}[/tex]. Take the square root of that to get x = 242,967.076 miles or, according to how your answer is to be stated, 243,000 miles.