Math
Parallel & Perpendicular Lines Calculator
Determine if two lines are parallel, perpendicular, or neither by analyzing their slopes.
Frequently Asked Questions
What makes lines parallel?
Two lines are parallel if they have the same slope and different y-intercepts. They never intersect. If slopes m1 = m2 and b1 ≠ b2, lines are parallel.
What makes lines perpendicular?
Two lines are perpendicular if the product of their slopes equals -1 (negative reciprocal). If m1 × m2 = -1, lines form 90° angle.
How do I find slope from an equation?
In y = mx + b form, m is the slope. From two points (x1,y1) and (x2,y2): slope = (y2 - y1) / (x2 - x1).
What is a negative reciprocal?
Negative reciprocal of m is -1/m. Example: reciprocal of 2 is 1/2; negative reciprocal is -1/2.
What if lines are neither parallel nor perpendicular?
They intersect at some angle other than 90°. Slopes are different and their product ≠ -1.