1. The magnitudes of vectors A, B and C are 3,4 and 5 units respectively. If A + B = C , then the angle between A and B is
(a) π/2
(b) \( cos^{−1}\, 0.6 \)
(c) \( tan^{−1}\, 7/5 \)
(d) π/4
Answer : (a) π/2
\(|\vec A+\vec B|=\sqrt{|\vec A|^2+|\vec B|^2+2|\vec A||\vec B|\cos\theta}=5\)
\(5^2=3^2+4^2+2(3)(4)\cos\theta\)
\(25=9+16+24\cos\theta\)
\(25=25+24\cos\theta\)
\(24\cos\theta=0\)
\(\cos\theta=0\)
\(\theta=\frac{\pi}{2}\)
No comments:
Post a Comment
Please provide your valuable feedback. Students, Parents, Teachers.