I will associate your vectors to have endpoints
P(7,10), Q(3,12) and R(-1,4)
then vector(PQ) = (-4,2)
vector(QR) = (-4,-8)
then PQ.QR = |PQ||QR|cos(theta), where theta is the angle between them
16-16 = |PQ||QR|cos(theta)
cos(theta) = 0
theta = 90 degrees
(notice the slope of lines PQ and QR are negative reciprocals of each other, so PQ and QR are perpendicular)
There are 3 vectors:
p= 7i + 10j
q= 3i + 12j
r= -i +4j
Could you show me how to find the angle PQR. using the scalar product.
1 answer
1 answer