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- 09:28, 24 March 2015 (diff | hist) . . (+661) . . N 1978 AHSME Problems/Problem 11 (Created page with "The circle <math>x^2 + y^2 = r</math> has center <math>(0,0)</math> and radius <math>\sqrt{r}</math>. Therefore, if the line <math>x + y = r</math> is tangent to the circle <m...")