Let line t be the line represented by 3x + 4y = 5 and let line p be the line perpendicular to line t and containing the point (5, 5). What is the x-coordinate of the point common to line t and line p ?
Line t: y=−34x+54
Perpendicular also means the "negative reciprocal of the slope" and in this case the negative reciprocal of the slope of Line t is 43.
Line p: y=43x+?
To find the y-intercept, we need to put in the point (5, 5) into Line p.
5=43(5)+? ---> 5=203+?---> 5−203=?---> −53=?
Line p: y=43x+−53
To find the point common to both lines, we set them equal to each other:
43x+−53=−34x+54
x=75
Since we only need the "x" coordinate, x=75 is our answer.
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