Question

given a.b=0 and a*b=0. what is the angle between a and b

Answer 1

Answer:

|a|=3,|b|=4,|c|=5

a+b+c=0

a+b =-c

|a+b| =|-c|

|a+b|2 =|-c|2

|a|2 +|b|2 +2a.b =|c|2

9 + 25 +2a.b=49

a.b=3*5

9+25+2ab cos theta=49

15=30cos theta

or cos theta=1/2

theata =60

so angle is 60 degrees