All SAT Math Resources
Example Questions
Example Question #5 : How To Find The Equation Of A Parallel Line
Which of these formulas could be a formula for a line perpendicular to the line ?
This is a two-step problem. First, the slope of the original line needs to be found. The slope will be represented by "" when the line is in -intercept form .
So the slope of the original line is . A line with perpendicular slope will have a slope that is the inverse reciprocal of the original. So in this case, the slope would be . The second step is finding which line will give you that slope. For the correct answer, we find the following:
So, the slope is , and this line is perpendicular to the original.
Example Question #392 : Geometry
Which of the following equations is parallel to: and goes through the point ?
Step 1: We need to define what a parallel line is. A parallel line has the same slope as the line given in the problem. Parallel lines never intersect, which tells us that the y-intercepts of the two equations are different.
Step 2: We need to identify the slope of the line given to us. The slope is always located in front of the .
The slope in the equation is .
Step 3: If we said that a parallel line has the same slope as the given line in the equation, the slope of the parallel equation is also .
Step 4. We need to write the equation of the parallel line in slope-intercept form:. We need to write b for the intercept because it has changed.
The equation is:
Step 5: We will use the point where and . We need to substitute these values of x and y into the equation in step 4 and find the value of b.
The numbers in red will cancel out when I multiply.
To find b, subtract 2 to the other side
Step 6: We put all of the parts together and make the final equation of the parallel line:
The final equation is:
Certified Tutor