Coordinate Geometry

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SSAT Upper Level Quantitative › Coordinate Geometry

Questions 1 - 10
1

What line is perpendicular to and passes through ?

Explanation

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 .

2

Consider the lines described by the following two equations:

4y = 3x2

3y = 4x2

Find the vertical distance between the two lines at the points where x = 6.

36

21

12

44

48

Explanation

Since the vertical coordinates of each point are given by y, solve each equation for y and plug in 6 for x, as follows:

Taking the difference of the resulting y -values give the vertical distance between the points (6,27) and (6,48), which is 21.

3

Which of the following lines is parallel with the line ?

Explanation

Parallel lines have the same slope. The slope of a line in slope-intercept form is the value of . So, the slope of the line is . That means that for the two lines to be parallel, the slope of the second line must also be .

4

Find the slope of the line perpendicular to the line that has the equation .

Explanation

Perpendicular lines have slopes that are negative reciprocals of each other. In other words, change the sign and flip the fraction around.

5

Consider the lines described by the following two equations:

4y = 3x2

3y = 4x2

Find the vertical distance between the two lines at the points where x = 6.

36

21

12

44

48

Explanation

Since the vertical coordinates of each point are given by y, solve each equation for y and plug in 6 for x, as follows:

Taking the difference of the resulting y -values give the vertical distance between the points (6,27) and (6,48), which is 21.

6

What is the slope of a line which passes through coordinates \dpi{100} \small (3,7) and \dpi{100} \small (4,12)?

\dpi{100} \small 5

\dpi{100} \small \frac{1}{5}

\dpi{100} \small \frac{1}{2}

\dpi{100} \small 2

\dpi{100} \small 3

Explanation

Slope is found by dividing the difference in the \dpi{100} \small y-coordinates by the difference in the \dpi{100} \small x-coordinates.

\dpi{100} \small \frac{(12-7)}{(4-3)}=\frac{5}{1}=5

7

Find the equation of a line that goes through the point and is parallel to the line with the equation .

Explanation

For lines to be parallel, they must have the same slope. The slope of the line we are looking for then must be .

The point that's given in the equation is also the y-intercept.

Using these two pieces of information, we know that the equation for the line must be

8

What line is perpendicular to and passes through ?

Explanation

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 .

9

Which of the following lines is parallel to the line ?

Explanation

For two lines to be parallel, their slopes must be the same. Thus, the line that is parallel to the given one must also have a slope of .

10

What is the slope of a line which passes through coordinates \dpi{100} \small (3,7) and \dpi{100} \small (4,12)?

\dpi{100} \small 5

\dpi{100} \small \frac{1}{5}

\dpi{100} \small \frac{1}{2}

\dpi{100} \small 2

\dpi{100} \small 3

Explanation

Slope is found by dividing the difference in the \dpi{100} \small y-coordinates by the difference in the \dpi{100} \small x-coordinates.

\dpi{100} \small \frac{(12-7)}{(4-3)}=\frac{5}{1}=5

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