A line segment is bisected by a line with the equation - 2 y - 5 x = 2 . If one end of the line segment is at ( 8 , 7 ), where is the other end?
1 Answer
Explanation:
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Put the line in
y -intercept formy = mx + b :
-2y = 5x + 2
y = -5/2x -1
m = -5/2
The perpendicular bisector slope= -1/m = 2/5 -
Find the equation for perpendicular bisector the line with
(8,7) :
y = 2/5x + b
7 = 2/5*(8/1) + b
7 = 16/5 + b
35/5 - 16/5 = 19/5
y = 2/5x + 19/5 -
Find the midpoint (intersection point) of the two lines
-5/2x -1 = 2/5x + 19/5
-5/2x - 2/5x = 19/5 + 1
-25/10x - 4/10 x = 19/5 + 5/5
-29/10x = 24/5
x = 24/5 * -10/29 = 24/1 * -2/29 = -48/29
#y = -5/2 * -48/29
midpoint point
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Length from midpoint to
(8,7) , 1/2 length of line segment:
sqrt((7 - 91/29)^2 + (8 --48/29)^2) = sqrt ((203/29 - 91/29)^2 + (232/29 + 48/29)^2) = sqrt((112/29)^2 + (280/29)^2) = sqrt((112^2+280^2)/(29^2) ) = sqrt(3136/29) = 56/sqrt(29) = (56sqrt(29))/29~~ 10.4 -
Length of the line segment:
2 * 56/sqrt(29) = 112/sqrt(29) = (112sqrt(29))/29 ~~ 20.8 -
Use proportions to find the endpoint:
x/(280/29) = (112/sqrt(29))/(56/sqrt(29)); " "x = 560/29
Endpoint
CHECK using the line equation & finding length:
Length of 1/2 line from