Values of trigonometric ratios of 18, 36 and related angles

1. A.
   $\cos 54^{\circ}$
2. B.
   $\cos 36^{\circ}$
3. C.
   $\sin 54^{\circ}$
4. D.
   $\sin 36^{\circ}$

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1. A.
   $\frac{-\sqrt{5}+1}{8}$
2. B.
   $\frac{\sqrt{5}-1}{8}$
3. C.
   $\frac{\sqrt{5}+1}{8}$
4. D.
   $\frac{-1-\sqrt{5}}{8}$

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1. A.
   $\frac{-\sqrt{5}+1}{8}$
2. B.
   $\frac{\sqrt{5}-1}{8}$
3. C.
   $\frac{\sqrt{5}+1}{8}$
4. D.
   $\frac{-\sqrt{5}-1}{8}$

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1. A.
   $\dfrac{-1 + \sqrt{5}}{4}$
2. B.
   $\dfrac{-1 + \sqrt{5}}{2}$
3. C.
   $\dfrac{1 + \sqrt{5}}{4}$
4. D.
   $\dfrac{1 - \sqrt{5}}{4}$

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