I'm not sure where you'd ask vector questions, but since this one involved I decided to ask it here:
Two vectors, a and b, have a common starting point with an angle of 120 degrees between them. The vectors are such that |a| = 3 and |b| = 4.
Calculate |a+b|
The way I thought of it was |a+b| = \sqrt{3^2+4^2-2(3)(4)(\cos{60})} = \sqrt {13}
However, the answer in the book is \sqrt {3}
Thanks! I had done that but the answer in the book threw me off.
Another question: Calculate the angle between vector a and vector a+b.
I would do sin60/sqrt{13}=sinx/4, where x is the angle, right? The answer in the book appears to be another typo, so I just wanted some clarification.