Common Core
G-GPE.B.5
3 lessons teach this standard. Every lesson is interactive, and every one prints as a worksheet with a separate answer key.
Algebra 1 · Chapter 4 · Lesson 4
Parallel and Perpendicular Lines
Same slope, or slopes that multiply to −1.
Geometry · Chapter 7 · Lesson 3
Proving Things with Coordinates
Turning a geometric claim into arithmetic.