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Question 756182: Given an equation of a line, find equations for lines parallel or perpendicular to it going through specified points. Find the appropriate equations and points from the table below. Simplify your equations into slope-intercept form.
For: Y= ¼ x -2; (8, -1)
Answer by Cromlix(4381)   (Show Source):
You can put this solution on YOUR website! Given line: y = 1/4x - 2
A line parallel to this line will
have an equal gradient = 1/4
Using the formula: and coords (8, -1)
y - b = m(x - a)
y + 1 = 1/4(x - 8)
4y + 4 = x - 8
4y = x - 8 - 4
4y = x - 12
or
y = 1/4x -3 (Divided by 4)
A line perpendicular to y = 1/4x - 2
will have a gradient = -4
This is because when lines are perpendicular
to each other their gradients multiply together
to equal -1
This case: m1 * m2 = 1/4 * -4 = -1
Using the formula: and coords (8, -1)
y - b = m(x - a)
y + 1 = -4(x - 8)
y + 1 = -4x + 32
y = -4x + 32 - 1
y = -4x + 31
Hope this helps.
:-)
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