We need to find dot products of 2 vectors:
u·v = x1*x2 + y1*y2
u·v = 2*(-6) + 3*4 = -12 + 12 = 0
Another way to write dot product u·v = |u|*|v|*cos α.
Because the do product = 0, we can write
|u|*|v|*cos α = 0.
That means cos α = 0, and thus α=90⁰, so vectors v and u are orthogonal.
