All SAT Math Resources
Example Questions
Example Question #4 : How To Find The Equation Of A Perpendicular Line
Give the equation of a line perpendicular to .
None of the other answers
The slope of a perpendicular line is the opposite reciprocal, therefore we are looking for a line with a slope of .
is the only answer choice that satisfies this criteria.
Example Question #5 : How To Find The Equation Of A Perpendicular Line
Find the equation of the line that is perpendicular to and passes through (5, 6).
We know that the slope of the original line is
Thus the slope of the perpendicular line is the negative reciprocal of , or –2.
Then we plug the slope and point (5, 6) into the form , which yields
When we simplify this, we arrive at
Example Question #1 : How To Find The Equation Of A Perpendicular Line
What line is perpendicular to through ?
We need to find the slope of the given equation by converting it to the slope intercept form: .
The slope is and the perpendicular slope would be the opposite reciprocal, or .
The new equation is of the form and we can use the point to calculate . The next step is to convert into the standard form of .
Example Question #7 : How To Find The Equation Of A Perpendicular Line
What line is perpendicular to and passes through ?
Perpendicular slopes are opposite reciprocals. The original slope is so the new perdendicular slope is 3.
We plug the point and the slope into the point-slope form of the equation:
to get or in standard form .
Example Question #71 : Geometry
Solve the system of equations for the point of intersection.
First one needs to use one of the two equations to substitute one of the unknowns.
From the second equation we can derive that y = x – 3.
Then we substitute what we got into the first equation which gives us: x + x – 3 = 15.
Next we solve for x, so 2x = 18 and x = 9.
x – y = 3, so y = 6.
These two lines will intersect at the point (9,6).
Example Question #431 : Sat Mathematics
Line A is perpendicular to and passes the point . Find the -intercept of line A.
We are given an equation of a line and told that line A is perpendicular to it. The slope of the given line is 2. Therefore, the slope of line A must be , since perpendicular lines have slopes that are negative reciprocals of each other.
The equation for line A will therefore take the form , where b is the y-intercept.
Since we are told that it crosses , we can plug in the point and solve for c:
Then the equation becomes .
To find the x-intercept, plug in 0 for y and solve for x:
Example Question #432 : Sat Mathematics
What line is perpendicular to through ?
The slope of the given line is , and the slope of the perpendicular line is its negative reciprocal, . We take the new slope and the given point and plug them into the slope-intercept form of a line, .
Thus, the perpendicular line has the equation , or in standard form, .
Example Question #51 : Lines
In the xy-plane, the equation of the line n is –x+8y=17. If the line m is perpendicular to line n, what is a possible equation of line m?
y= -1/8x + 5
x= -8y + (17/8)
y= -8x + 5
y= 8x-17
y= -8x + 5
We start by add x to the other side of the equation to get the y by itself, giving us 8y =17 + x. We then divide both sides by 8, giving us y= 17/8 + 1/8x. Since we are looking for the equation of a perpendicular line, we know the slope (the coefficient in front of x) will be the opposite reciprocal of the slope of our line, giving us y= -8x + 5 as the answer.
Example Question #1 : How To Find The Equation Of A Perpendicular Line
What line is perpendicular to x + 3y = 6 and travels through point (1,5)?
y = 2/3x + 6
y = 2x + 1
y = 3x + 2
y = –1/3x – 4
y = 6x – 3
y = 3x + 2
Convert the equation to slope intercept form to get y = –1/3x + 2. The old slope is –1/3 and the new slope is 3. Perpendicular slopes must be opposite reciprocals of each other: m1 * m2 = –1
With the new slope, use the slope intercept form and the point to calculate the intercept: y = mx + b or 5 = 3(1) + b, so b = 2
So y = 3x + 2
Example Question #1 : How To Find The Equation Of A Perpendicular Line
What line is perpendicular to and passes through ?
Convert the given equation to slope-intercept form.
The slope of this line is . The slope of the line perpendicular to this one will have a slope equal to the negative reciprocal.
The perpendicular slope is .
Plug the new slope and the given point into the slope-intercept form to find the y-intercept.
So the equation of the perpendicular line is .