$\begin{array}{l}A=\sin {78}^{\circ }-\sin {18}^{\circ }+\cos {132}^{\circ }\\ B=\cos {12}^{\circ }+\cos {84}^{\circ }+\cos {132}^{\circ }+\cos {156}^{\circ }\text{ and }\\ C=\frac{\sin {75}^{\circ }+\sin {15}^{\circ }}{\cos {75}^{\circ }+\cos {15}^{\circ }}\text{ then arrange in the ascending order }\end{array}$

$B=\cos {12}^{\circ }+\cos {84}^{\circ }+\cos {132}^{\circ }+\cos {156}^{\circ }=$

$=\left(\cos 132°+\cos 12°\right)+\left(\cos 156°+\cos 84°\right)$

$=2\cos \frac{132°+12°}{2}\cos \frac{132°-12°}{2}+2\cos \frac{156°+84°}{2}\cos \frac{156°-84°}{2}$

$=2\cos 72°\cos 60°+2\cos 120°\cos 36°$

$=2\sin 18°\left(\frac{1}{2}\right)+2\left(\frac{-1}{2}\right)\cos 36°$

$=\sin 18°-\cos 36°$

$\frac{\sqrt{5}-1}{4}-\frac{\sqrt{5}+1}{4}$

$B=\frac{-1}{2}$

$$\begin{gathered} A=\sin {78}^{\circ }-\sin {18}^{\circ }+\cos {132}^{\circ } \\ A=2\cos \frac{78°+18°}{2}\sin \frac{78°-18°}{2}+\cos \left(180°-48°\right) \end{gathered}$$

$A=2\cos 48°\sin 30°-\cos 48°$

$A=\cos 48°-\cos 48°=0$

$C=\frac{\sin {75}^{\circ }+\sin {15}^{\circ }}{\cos {75}^{\circ }+\cos {15}^{\circ }}=\frac{2\sin 45°\cos 30°}{2\cos 45°\cos 30°}=1$

$\mathrm{B},\mathrm{A},C$