Question

The angle between the two vectors a= 3i+4j+5k and b=3 i +4j+5k

Answer 1

First, find the dot product of the vectors, letting u=3i+4j+5k and v=3i+4j−5k:

u⋅v=9+16−25=25−25=0

Recall that if the dot product of two vectors is 0, then they are perpendicular.

Thus, the angle between vectors u and v is 90° or π2, depending on your preference between radians and degrees.

I hope this helps.