1. Given four points A1 (x1, y1, z1), A2 (x2, y2, z2), A3 (x3, y3, z3), A4 (x4, y4, z4)
 Be the equation:
 a) a plane A1A2A3; b) direct A1A2;
 c) direct A4M perpendicular to the plane A1A2A3;
 g) direct A3N, parallel line A1A2;
 d) a plane passing through the point perpendicular to the line A4 A1A2.
 Calculated:
 e) The sine of the angle between the line and the plane A1A4 A1A2A3;
 g) the cosine of the angle between the coordinate plane and the plane Oxy A1A2A3;
 1.20 A1 (1, 1, 3), A2 (6, 5, 8), A3 (3, 5, 8), A4 (8, 4, 1)

2. Solve the following tasks
 2.20 Write the equation of the plane passing through the axis Oy and the point M (3, -5, 2).

3. Solve the following tasks
 At what value of 3.20 D direct 3x-y + 2z-6 = 0, x + 4y-z + D = 0 intersects the axis Oz?