Question

7. The vectors a,b,c satisfy the condition
a+b+2c=7. If |āl=1,|b|= 4, |c| = 2, the
a.b +b.c +c.a =​

Answer 1

Step-by-step explanation:

Given a + b +c = 0 ==>a•(a + b +c) = a•0 or a•a + a•b + a•c = 0 ==> a•b + a•c =- 1 (a•a = a^2 = 1^2 = 1) . Similarly we can get a•b + c•b = -16 and a•c + b•c = -4 . Adding these three equations, we get, 2(a•b + b•c + c•a) = -1 -16 - 4 =-21 which in turn gives (a•b + b•c + c•a) = -21/2 .

hope it help you

Answer 2

Answer:

1/12 apply |a+b+c|² and calculate the value by putting all the know value