All PSAT Math Resources
Example Questions
Example Question #1 : How To Find The Slope Of Parallel Lines
In the xy-plane, what is the equation for a line that is parallel to and passes through the point ?
In order to solve the equation for this line, you need to things: the slope, and at least one point. You are already given a point for the line, so you just need to figure out the slope. The other piece of information you have is a line parallel to the line that you're looking for; since parallel lines have the same slope, you just need to figure out the slope of the parallel line you've already been given.
To figure out the slope, change the equation into point-slope form (y = mx+b) so the slope m is easy to find. To do that, you need to isolate y on one side of the equation.
By the calculations above, you'll find that the slope of the parallel line is -1/2.
Now, use this slope of -1/2 and the point 4,1 to find the equation. First, plug them both into the point-slope form, then solve for the slope-intercept form.
Example Question #1 : How To Find The Equation Of A Parallel Line
Which of the following is the equation of a line that is parallel to the line 4x – y = 22 and passes through the origin?
y – 4x = 22
4x + 8y = 0
(1/4)x + y = 0
4x = 8y
4x – y = 0
4x – y = 0
We start by rearranging the equation into the form y = mx + b (where m is the slope and b is the y intercept); y = 4x – 22
Now we know the slope is 4 and so the equation we are looking for must have the m = 4 because the lines are parallel. We are also told that the equation must pass through the origin; this means that b = 0.
In 4x – y = 0 we can rearrange to get y = 4x. This fulfills both requirements.
Example Question #2 : Coordinate Geometry
What line is parallel to 2x + 5y = 6 through (5, 3)?
y = 5/2x + 3
y = 5/3x – 5
y = –2/3x + 3
y = 3/5x – 2
y = –2/5x + 5
y = –2/5x + 5
The given equation is in standard form and needs to be converted to slope-intercept form which gives y = –2/5x + 6/5. The parallel line will have a slope of –2/5 (the same slope as the old line). The slope and the given point are substituted back into the slope-intercept form to yield y = –2/5x +5.
Example Question #3 : Coordinate Geometry
What line is parallel to through ?
The slope of the given line is and a parallel line would have the same slope, so we need to find a line through with a slope of 2 by using the slope-intercept form of the equation for a line. The resulting line is which needs to be converted to the standard form to get .
Example Question #114 : Psat Mathematics
Find the equation of a line parallel to that also passes through the point .
Since they are parallel, the line will have the same slope as .
Thus, it will take the form .
We then use the point (3,2) to solve for :
so the equation of the line is
Example Question #1 : How To Find The Equation Of A Parallel Line
In the -plane, the line is parallel to the line . What is the value of ?
In this equation, is equal to the slope of the line. You have been given a line parallel to the line containing variable , and since parallel lines have the same slope, all you need to do is figure out the slope of in order to figure out what is. To figure out the slope of , you need to convert the equation into form, which means isolating on one side of the equation.
Given this solution, the slope of the parallel lines, and thus , is equal to 2.
Example Question #1 : How To Find The Equation Of A Parallel Line
Which of the following lines has zero points of intersection with the line, ?
This prompt asks you to find a line that is parallel to the one given. Parallel lines have no points of intersection (as opposed to intersecting lines which have 1 point of intersection). Parallel lines have the same slope, but different y-intercepts. If they had the same y-intercept, then they would actually be the same line.
We can find the slope of the first line by converting it to slope-intercept form.
First, subtract 3x from both sides.
Then, divide both sides by -2.
The slope of the line is 3/2. The only answer that has that same slope, but a different y-intercept is .
Example Question #1 : How To Find An Angle Of A Line
Two angles are supplementary and have a ratio of 1:4. What is the size of the smaller angle?
Since the angles are supplementary, their sum is 180 degrees. Because they are in a ratio of 1:4, the following expression could be written:
Example Question #1 : How To Find An Angle Of A Line
AB and CD are two parrellel lines intersected by line EF. If the measure of angle 1 is , what is the measure of angle 2?
The angles are equal. When two parallel lines are intersected by a transversal, the corresponding angles have the same measure.
Example Question #1 : Geometry
Figure not drawn to scale.
In the figure above, APB forms a straight line. If the measure of angle APC is eighty-one degrees larger than the measure of angle DPB, and the measures of angles CPD and DPB are equal, then what is the measure, in degrees, of angle CPB?
66
50
33
114
40
66
Let x equal the measure of angle DPB. Because the measure of angle APC is eighty-one degrees larger than the measure of DPB, we can represent this angle's measure as x + 81. Also, because the measure of angle CPD is equal to the measure of angle DPB, we can represent the measure of CPD as x.
Since APB is a straight line, the sum of the measures of angles DPB, APC, and CPD must all equal 180; therefore, we can write the following equation to find x:
x + (x + 81) + x = 180
Simplify by collecting the x terms.
3x + 81 = 180
Subtract 81 from both sides.
3x = 99
Divide by 3.
x = 33.
This means that the measures of angles DPB and CPD are both equal to 33 degrees. The original question asks us to find the measure of angle CPB, which is equal to the sum of the measures of angles DPB and CPD.
measure of CPB = 33 + 33 = 66.
The answer is 66.