WBJEE · Physics · Mathematics in Physics
If \(\vec{a}+\vec{b}=\vec{c}\) and \(a+b=c\), then the angle included between \(\vec{a}\) and \(\vec{b}\) is
- A \(90^{\circ}\)
- B \(180^{\circ}\)
- C \(120^{\circ}\)
- D Zero
Answer & Solution
Correct Answer
(D) Zero
Step-by-step Solution
Detailed explanation
Hints: Here \(\vec{a}+\vec{b}=\vec{c} \& c=a+b\) Now, \(c=\sqrt{a^2+b^2+2 a b \cos \theta}\) \(\begin{aligned} & (a+b)=\sqrt{a^2+b^2+2 a b \cos \theta} \\ & a^2+b^2+2 a b=a^2+b^2+2 a b \cos \theta \\ & \cos \theta=1, \theta=0^{\circ} \end{aligned}\)
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