Number 1 are given the vector. It is necessary: ​​a) to calculate the mixed product of three vectors; b) find the module of the vector product; c) calculate the scalar product of two vectors; d) check whether two vectors are collinear or orthogonal; e) check whether three vectors will be coplanar: a (9; -3; 1); b (3; -15; 21); c (1; -5; 7).

No. 2 The tops of the pyramid are at points A (5; –4; 4); B (–4; –6; 5); C (3; 2; –7); D (6; 2; –9) ...

No. 3 Given three forces P (–5; 8; 4); Q (6; –7; 3); R (3; 1; –5); applied to point A (2; –4; 7). Calculate a) the work produced by the resultant of these forces; when the point of its application, moving rectilinearly, moves to point B (0; 7; 4); b) the value
the moment of the resultant of these forces with respect to point B.