cos(630) ≈ 0.8253
sin(1470) ≈ 0.4339
ctg(1125) = 1 / tan(1125)

Let's find tan(1125) first:
tan(1125) = sin(1125) / cos(1125) ≈ 4.7536

Therefore, ctg(1125) = 1 / tan(1125) ≈ 0.2105

Now,
cos(630) - sin(1470) - ctg(1125)
≈ 0.8253 - 0.4339 - 0.2105
≈ 0.1809.

So, the value of the expression is approximately 0.1809.