№1 Given four points A1 (2; 4; 3); A2 (1; 1; 5); A3 (4; 9; 3); A4 (3; 6; 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;

№2 Make an equation for the plane passing through point A (2; –3; 5) parallel to the Ohu plane.

No. 3 Prove that the line .. is perpendicular to the line ...