# Parallel and Perpendicular Lines

• Mar 20th 2007, 11:28 PM
Patience
Parallel and Perpendicular Lines
1. Find the slope of any line perpendicular to the line through points (0, 5) and (-3, -4).

Write the equation of the line L satisfying the given geometric conditions.

2. L has y-intercept (0, -3) and is parallel to the line with equation
y = 2/3x + 1
• Mar 21st 2007, 12:13 AM
DistantCube
1.
We know that the slope of a line that is perpindicular to the other is equal to the negative recipricol of the known slope. That is to say; if the slope of a line is 1/2 then the slope of a line perpindicular to the first is -2. Or more formally;
m1.m2 = -1 ;where m1 and m2 are the respective slopes.

So for this question, you just use the slope equation;
m=(y2-y1)/(x2-x1)

and apply the above theory.

2.
You know the slope of the line they've given you the equation for is 2/3 by y=mx+b. So therefore you know the slope of the line you want is also 2/3 as it is parallel (has the same slope). Now you just need to find the equation, they've given you a point, so just use the line formula;

y-y1=m(x-x1)

where y1 and x1 are your x and y points that are given to you and 'y' and 'x' are left as variables, rearrange the equation.

Don't forget to hit the thanks button on the posts of people that help you, especially if you make multiple threads. ;) If you need clarification on any points, just ask.