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A line and a circle intersect at A and B. Find the coordinates of the midpoint of \overline{AB}.
The ilne is y = 3x - 2, and the circle is (x - 4)^4 + (y - 5)^2 = 68.

 Jan 17, 2024
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y=3x + 2    (1)

(x-4)^2 + (y -5)^2  = 68   

 

The center of the circle is  (4, 5)

 

The slope  of the given line is  3

 

The slope of a perpendicular line is  -1/3

 

Using (4,5)  and writing an equation for this perpendicular  line gives us

 

y = -(1/3)(x -4) + 5

y = (-1/3)x + 4/3 + 5

y = (-1/3)x + 19/3

 

Finding the x intersection of these  two lines

 

3x + 2 = (-1/3)x + 19/3

9x + 6 = -x + 19

10x = 13

x = 13/10 

 

y = 3(13/10) + 2 =  47/4

 

The coordinates of the  midpoint  = (13/10, 59/10)

 

 

cool cool cool

 Jan 18, 2024

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