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  1. #1
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    vectors 4

    (a)Is triangle ABC a right-angled triangle? Justify your answer.
    [Note: A right-angled triangle is a triangle with one 90o internal angle.]


    Vector AB is ( 3, 6 , 1)
    Vector BC is ( 0 , -7 , -4)
    Vector CA is ( -3 , 1 , 3)
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    Quote Originally Posted by daphnewoon View Post
    (a)Is triangle ABC a right-angled triangle? Justify your answer.
    [Note: A right-angled triangle is a triangle with one 90o internal angle.]


    Vector AB is ( 3, 6 , 1)
    Vector BC is ( 0 , -7 , -4)
    Vector CA is ( -3 , 1 , 3)
    Take the three dot products, see if one of them is 0.
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    the x part is zero. thus it is a right-angled triangle?
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    No.

    Do what I said.

    Find A\cdot B, A\cdot C and B\cdot C, and see if any of these dot products are 0. If so, you have a right angle.


    If you do not know anything about dot products (also known as scalar products) I suggest you do a Google search.
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