Question 364482
Show that vectors a = 2i-4j-k, b = 3i+2j-2k and c = 5i-2j-3k can form the sides of a triangle, find the length of each side and hence show that the triangle has a right angle. sketch the triangle of vectors, indicating their directions and the right angle, 
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Find the lengths:
{{{s = sqrt(i^2 + j^2 + k^2)}}}
a: {{{s = sqrt(4 + 16 + 1) = sqrt(21)}}}
a: s = sqrt(21)
b: s = sqrt(17)
c: s = sqrt(38)
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c^2 is = a^2 + b^2, so it's a right triangle.