Angle between unit vectors a and b from |a + b| or |a - b|

1. A.
   $\frac{\pi}{3}$
2. B.
   $\frac{2\pi}{3}$
3. C.
   $\frac{\pi}{2}$
4. D.
   $\frac{\pi}{4}$

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1. A.
   $|\overline{a} - \overline{b}|$
2. B.
   $|\bar{a} + \bar{b}|$
3. C.
   $\frac{|\overline{a} + \overline{b}|}{|\overline{a} - \overline{b}|}$
4. D.
   $\frac{|\overline{a} - \overline{b}|}{|\overline{a} + \overline{b}|}$

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1. A.
   $\frac{\pi}{6}$
2. B.
   $\frac{\pi}{3}$
3. C.
   $\frac{\pi}{4}$
4. D.
   $\frac{\pi}{2}$

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1. A.
   $\tan\dfrac{\theta}{2}$
2. B.
   $\sin\dfrac{\theta}{2}$
3. C.
   $\cos\dfrac{\theta}{2}$
4. D.
   $\cot\dfrac{\theta}{2}$

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1. A.
   $\sqrt{2}$
2. B.
   $0$
3. C.
   $\sqrt{5}$
4. D.
   $\sqrt{3}$

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1. A.
   $0^\circ$
2. B.
   $45^\circ$
3. C.
   $90^\circ$
4. D.
   $180^\circ$

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