№1 Given four points A1 (1; –2; 7); A2 (4; 2; 10); A3 (2; 3; 5); A4 (5; 3; 7). Draw up the equations: a) plane A1A2A3; b) straight line A1A2; c) direct A4M; perpendicular to the plane A1A2A3; d) direct A3N; parallel line A1A2; e) a plane passing through point A4; perpendicular to the straight line A1A2; Calculate: e) the sine of the angle between the straight line A1A4 and the plane A1A2A3; g) the cosine of the angle between the Ohu coordinate plane and the A1A2A3 plane.

No. 2 Make the equation of the plane; which passes through the points M (1; 2; 3) and N (–3; 4; –5) parallel to the z axis.

№3 At what value are lines p; lines are parallel.