Question
If $|\vec{a}|=1=|\bar{b}|$ and $|\vec{a}+\bar{b}|=\sqrt{3}$, then $(2 \bar{a}-5 \bar{b}) \cdot(3 \bar{a}+\bar{b})$ is equal to(a) $-\frac{11}{2}$(b) $\frac{11}{2}$(c) $-11$(d) 11
Step 1
Substituting the given values, we get $\sqrt{3}^2=1^2+1^2+2*1*1*cos\theta$, which simplifies to $3=2+2cos\theta$. Solving for $cos\theta$, we get $cos\theta=\frac{1}{2}$, which implies that $\theta=60^{\circ}$. Show more…
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