Find cos(105∘)\cos(105^\circ)cos(105∘) exactly.
2−64\frac{\sqrt{2}-\sqrt{6}}{4}42−6
6−24\frac{\sqrt{6}-\sqrt{2}}{4}46−2
−2−64\frac{-\sqrt{2}-\sqrt{6}}{4}4−2−6
2+64\frac{\sqrt{2}+\sqrt{6}}{4}42+6