1. Show that this expression is a total differential of the function u (x, y). Find u (x, y) function
1.11. (Ycos (xy) + 2x - 3y) dx + (xcos (xy) - 3x + 4y) dy

2. Solve the following tasks:
2.11. Calculate the coordinates of the center of mass of a spherical triangle homogeneous contour x2 + y2 + z2 = 1, x ≥ 0, y ≥ 0, z ≥ 0.

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