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PSAT Math › Lines
One line has four collinear points in order from left to right A, B, C, D. If AB = 10’, CD was twice as long as AB, and AC = 25’, how long is AD?
45'
40'
50'
35'
30'
Explanation
AB = 10 ’
BC = AC – AB = 25’ – 10’ = 15’
CD = 2 * AB = 2 * 10’ = 20 ’
AD = AB + BC + CD = 10’ + 15’ + 20’ = 45’
Whast line goes through the points 
Explanation
Let 
The slope is geven by: 
Then we use the slope-intercept form of an equation; 
And we convert
to standard form.
A line segment has endpoints (0,4) and (5,6). What are the coordinates of the midpoint?
(0,4)
(0,6)
(2.5,-5)
(2.5,5)
(3,9)
Explanation
A line segment has endpoints (0,4) and (5,6). To find the midpoint, use the midpoint formula:
X: (x1+x2)/2 = (0+5)/2 = 2.5
Y: (y1+y2)/2 = (4+6)/2 = 5
The coordinates of the midpoint are (2.5,5).
A line segment has endpoints (0,4) and (5,6). What are the coordinates of the midpoint?
(0,4)
(0,6)
(2.5,-5)
(2.5,5)
(3,9)
Explanation
A line segment has endpoints (0,4) and (5,6). To find the midpoint, use the midpoint formula:
X: (x1+x2)/2 = (0+5)/2 = 2.5
Y: (y1+y2)/2 = (4+6)/2 = 5
The coordinates of the midpoint are (2.5,5).
What line is perpendicular to 
Explanation
Convert the given equation to slope-intercept form.
The slope of this line is 
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 
A line segment has endpoints (0,4) and (5,6). What are the coordinates of the midpoint?
(0,4)
(0,6)
(2.5,-5)
(2.5,5)
(3,9)
Explanation
A line segment has endpoints (0,4) and (5,6). To find the midpoint, use the midpoint formula:
X: (x1+x2)/2 = (0+5)/2 = 2.5
Y: (y1+y2)/2 = (4+6)/2 = 5
The coordinates of the midpoint are (2.5,5).
One line has four collinear points in order from left to right A, B, C, D. If AB = 10’, CD was twice as long as AB, and AC = 25’, how long is AD?
45'
40'
50'
35'
30'
Explanation
AB = 10 ’
BC = AC – AB = 25’ – 10’ = 15’
CD = 2 * AB = 2 * 10’ = 20 ’
AD = AB + BC + CD = 10’ + 15’ + 20’ = 45’
What line is perpendicular to
Explanation
Convert the given equation to slope-intercept form.
The slope of this line is
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
Explanation
One line has four collinear points in order from left to right A, B, C, D. If AB = 10’, CD was twice as long as AB, and AC = 25’, how long is AD?
45'
40'
50'
35'
30'
Explanation
AB = 10 ’
BC = AC – AB = 25’ – 10’ = 15’
CD = 2 * AB = 2 * 10’ = 20 ’
AD = AB + BC + CD = 10’ + 15’ + 20’ = 45’