Homework Help Forum: Help on Vectors & Geometry

Posted by Wellness on Thursday, October 29, 2009 at 3:11pm.

(a) Given that A= 3i - j + 2k and B=2i + 3j - k find A x B (b) if A= i + j, B= 2i - 3j + k and C= 4j - 3k find (i) (AxB)x C (ii) Ax(BxC)

• Help on Vectors & Geometry - bobpursley, Thursday, October 29, 2009 at 6:19pm

  I will do one. These are much easier to do as matrix multipication on your calc, I would learn to do that. 1) AxB= (3i-j+2k)x(2i+3j-k) = 3*3ixj-3ixk-2jxi+jxk+4kxi+6kxj well, ixj=k jxk=i kxi=j (and the opposite order means -) AxB= 9k+3j+2k+i+4j-6i check that, and combine terms.

  
  

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