It actually depends upon the particular trapezius. (Trapezoid?) However, a few ground rules:

There are 4 internal angles - 2 sets of 2 equal ones. The total of the 4 must equal 360 degrees. So, for example, if the 2 top angles are 60 degrees each, then the two bottom ones must be 120 degrees each.

Look in a geometry book for the shape of a trapezoid, and this will be clearer.

There are 4 internal angles - 2 sets of 2 equal ones. The total of the 4 must equal 360 degrees. So, for example, if the 2 top angles are 60 degrees each, then the two bottom ones must be 120 degrees each.

Look in a geometry book for the shape of a trapezoid, and this will be clearer.