Parallel lines from equationParallel lines from equation (example 2)Parallel lines from equation (example 3)Perpendicular lines from equationWriting equations of perpendicular linesWriting equations of perpendicular lines (example 2)Proof: parallel lines have the same slopeProof: perpendicular lines have negative reciprocal slope
Classifying quadrilaterals on the coordinate plane
About this unit
In analytic geometry, also known as coordinate geometry, we think about geometric objects on the coordinate plane. For example, we can see that opposite sides of a parallelogram are parallel by writing a linear equation for each side and seeing that the slopes are the same.