Let L1 be the line with the vector equation r= (-2,3) +s(-1,3), seR. Let L2 be with the line with parametric equation x=3t+2, y=t-7, teR. Are L1 and L2 perpendicular? How do you know?

Answer 1

You have to look at their direction numbers

direction of L1 is (-1,3)

for L2, the direction is (3,1)

since (3,1)⋅(-1,3) = 0 , they are perpendicular.