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**lolz** 1. Suppose that the coordinates of points A, B and C with respect to a Cartesian coordinate system Oxyz are (1, -2, 2), (3, 0, -1) and (-1, 1, 4), respectively. Show that the triangle ABC is isosceles (that is, has two sides of the same length).

2. Let P and Q be the points (2, 3, -2) and (3, 2, -2), respectively. Find the vector equation of the line PQ.

3. What is the equation of the straight line through the points (2, -2, -1) and (4, 1, 5)? Find the shortest distance from the point (2, 1, 1) from this line.