If \(|\vec a|=2\), \(|\vec b|=3\) and \(|\vec a+\vec b|=\sqrt{19}\), the angle between \(\vec a\) and \(\vec b\) is
A. \(\frac{\pi}{6}\)
B. \(\frac{\pi}{3}\)
C. \(\frac{\pi}{2}\)
D. \(\frac{2\pi}{3}\)
1 answer
Best answer
Answer: B. \(\frac{\pi}{3}\)
\(19=4+9+2\vec a\cdot\vec b\Rightarrow\vec a\cdot\vec b=3=6\cos\theta\Rightarrow\cos\theta=\frac12\).
Maths Tutor AI
· 23 Oct 2026
AI-verified
AI-generated
Report
Your answer
Log in or create a free account to answer this question.