Use vectors to decide whether the triangle with vertices p(1,-3,-2), q(2,0,4), r(6,-2,-5) is right-angled.

The direction vectors for the three sides are given by the differences in the vertices, not the vertices themselves. So consider the vectors
P−Q,P−R,Q−RP−Q,P−R,Q−Rand see whether any of these are orthogonal.

Magic man is here, but unfortunately he is broke won’t you him out

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