# Evaluate a. (a + b +c)Watch

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#1
Hey =) All i can say on this question is help! lol. If any1 could help me on this, it would b much appreciated!

Q4) The sides of this equilateral triangle (in attatchment) are 2 units long & represent the vectors a,b, & c.

Evaluate a. (a + b +c)

I guess ya need to find the components of these vectors, but I just dont know how...maybe I'm missing sommin important here that one of you guys might notice.

Thanx xx
0
13 years ago
#2
Since a + c = b,

a.(a + b + c)
= a.(2b)
= 2 a.b

Now use a formula for the dot product.
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