Question

Are these lines parallel or not: L1: (1,2), (3,1), and L2: (0,-1), (2,0)

Answer 1

First find the slope of the first line

L1

m = ( y2-y1)/(x2-x1)

m = ( 1-2)/(3-1)

= -1/2

Now find the slope of the second line

L2

m= ( y2-y1)/(x2-x1)

= ( 0 - -1)/(2 -0)

= (0+1)/(2-0)

= 1/2

Parallel lines have the same slope

These lines do not have the same slope, they are different by a negative sign.

These lines are not parallel.