If the cos 90° = 0, then the sin 0° = (1 point)

Sine and cosine are cofunctions in trigonometry. When you have two angles that are complements (and sum to 90 degrees), the sine of that angle is the cosine of its complement.  (Look, for example, at a 30-60-90 triangle  - - the sine of 30 degrees is the cosine of 60 degrees)

Or, as a formula, sin x° = cos (90 - x)° and cos x° = sin (90 - x)°.

We are told that the cosine of 90° is 0. Let's use our cofunction definiton.

cos (90°) = sin (90 - 90)°         definition of cofunction

cos 90° = sin 0°

Since cos 90° = 0 then cos 90° = sin 0° = 0

Thus, sin(0°) = 0