The Mean Value Theorem: Quiz


Problem 7

Find the point on the unit circle centered at the origin that is closest to (4,1).


Answers, problem 7

If we draw the line from the origin to (4, 1), it passes through (x, y) on the circle. (x, y) will be the closest point on the circle to (4, 1). The slope of the line is 1/4, so y/x = 1/4, or x = 4y. x and y satisfy x2 + y2 = 1, so (4y)2 + y2 = 1, 17y2 = 1, so y = approximately 0.243 and x = approximately 0.97.


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