Question

If a,b,c are vectors such that a+b+c=0 and |a|=7 |b|=5 |c|=3 then the angle between b and c is ?

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

mark brainliest plzzzzz

Step-by-step explanation: