Answer:
By looking at the slope
Step-by-step explanation:
Let's use these equation: y = 2x + 3 and y = 2x - 9
You know that those two equations are parallel because the slope is the exact same!
But, if we rewrite those equations to: y = -2x + 3 and y = 1/2x - 9
You can now see that the equations are perpendicular because the slopes are Opposite Reciprocal. The slopes have opposite signs (pos./neg.) and are reciprocal numbers: 2 = 1/2
