SOLUTION: Write the equation of the line tangent to go (x-4)^2 +y^2 = 25 at x = 9

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Question 1063885: Write the equation of the line tangent to go (x-4)^2 +y^2 = 25 at x = 9
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
One of the points on this circle is (9,0), the only point on this circle for which x=0. The circle has center at (4,0), so this radius (of length 5) from center to x=9 on the circle is perpendicular to the desired tangent line at x=9, which means, this tangent line is vertical, having undefined slope.

The line asked for in the question is x=9.

No taking of derivative needed.