SOLUTION: Write the equation of the tangent to circle {{{ x^2+(y-4)^2=16 }}} at P(-4,4)

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Question 406852: Write the equation of the tangent to circle +x%5E2%2B%28y-4%29%5E2=16+ at P(-4,4)
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Write the equation of the tangent to circle +x%5E2%2B%28y-4%29%5E2=16+ at P(-4,4)
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x^2+(y-4)^2=16
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x^2 + y^2 - 8y + 16 = 16
2xdx + 2ydy - 8dy = 0
xdx + (y-4)dy = 0
xdx = (4-y)dy
dy/dx = x/(4-y)
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@ (-4,4):y' = -4/0 --> undefined, parallel to y-axis
--> x = -4