Evaluate:

A speaks truth in 75% of the cases, while B in 90% of the cases. In what percent of cases are they likely to contradict each other in stating the same fact?

Do you think that statement of B is true?

Using vectors, find the area of the triangle ABC with vertices A (1, 2, 3), B (2, –1, 4) and C(4, 5, –1).

Evaluate:

Find the coordinate of the point where the line through (3, –4, –5) and (2, –3, 1) crosses the plane, passing through the points (2, 2, 1), (3, 0, 1) and (4, –1, 0).