Calculus
posted by Samantha .
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=t7, teR. Are L1 and L2 perpendicular? How do you know?

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.