1. The Slope Formula:
Between (­19, ­16) and (­3, 14):
If two lines have the same slope, they must be __________.
If two lines have opposite­sign, reciprocal slopes, they must
be ________________.

2. The Midpoint Formula:
Between (­19, ­16) and (­3, 14):
If one endpoint is (3,9) and the midpoint is (0,5), find the
other endpoint:

3. Example: Prove that the triangle with vertices at A(2, 0)
B(­6, 4) and C(­10, ­4) is an isosceles, right triangle.