Midpoint Formula
2.5 Slope and Midpoint
I CAN...
Apply midpoint formula to find missing endpoints
Apply slope formula to show lines are parallel, perpendicular, or interesting
Jul 11­10:27 AM
Find the midpoint of the segment with endpoints (2, 7) and (5, 3).
Jul 15­10:25 AM
Find the missing endpoint of the segment with endpoint (3, ­5) and midpoint (­1, 2).
Jul 15­10:25 AM
The midpoint between points (x1, y1) and (x2, y2) is:
M=
Jul 15­10:25 AM
Find the midpoint of the segment with endpoints (­4, ­6) and (5, ­1).
Jul 15­10:25 AM
Find the coordinates of the missing endpoint if B is the midpoint of AC, C(­7, ­4) and B(3, 5)
Jul 15­10:25 AM
1
Slope Formula
Remember: y=mx+b
Given (x1, y1) and (x2, y2) the slope of the line is:
y2­y1
m = Slopes of Parallel Lines have the same slope
1
y = x + 3
2
and 1
y = x ­ 5
2
x ­x
2
1
Slopes of Perpendicular Lines have negative reciprocal slopes
m = rise
run
1
y = x + 3
4
Jul 15­10:25 AM
and y = ­4x ­ 7
Jul 15­10:25 AM
Parallel, Perpendicular, or Intersecting?
FG
F ( 1, ­3 ) and G ( ­2, ­1 )
HJ
H ( 5, 0 ) and J ( 6, 3 )
Jul 15­10:25 AM
Parallel, Perpendicular, or Intersecting?
AB
A ( ­2, ­1 ) and B ( 4, 5 )
CD
C ( 6, 1 ) and D ( 9, ­2 )
Jul 15­10:25 AM
Quadrilateral WXYZ is graphed below. Is WX ZY?
Explain
W
X
Is WZ ZY?
Explain
Z
Y
Jul 15­10:25 AM
2