№1 Given four points A1 (10; 9; 6); A2 (2; 8; 2); A3 (9; 8; 9); A4 (7; 10; 3). Draw up the equations: a) plane A1A2A3; b) straight line A1A2; c) a straight line A4M perpendicular to the plane A1A2A3; d) line A3N parallel to line A1A2; e) a plane passing through point A4, perpendicular to the 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 the origin perpendicular to the vector AB, if A (5; –2; 3); B (1; –3; 5).

№3 Draw up the equation of the line passing through the point M (2; –3; 4-) perpendicular to the lines ..... and .....