The product cos 1° cos 2° ... cos 180° equals zero. This is because one of the terms in this sequence is cos 90°.

We know that cos 90° = 0. The multiplication of any series of numbers, no matter how large, by zero will always result in zero. Therefore, the entire product is:

$\cos \mathrm{1°}\times \cos \mathrm{2°}\times \dots \times \cos \mathrm{90°}\times \dots \times \cos \mathrm{180°}=0$

Final Answer: 0