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Math Help - How to find area of triangle with two vertices?

  1. #1
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    How to find area of triangle with two vertices?

    How do I find the area of a triangle with two sides given by a = <1,3,-1> and b = <2,-1,2>? Thank you.
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  2. #2
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    Quote Originally Posted by henrymath View Post
    How do I find the area of a triangle with two sides given by a = <1,3,-1> and b = <2,-1,2>? Thank you.
    what does |\vec{a} \times \vec{b}| get you?
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  3. #3
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    Quote Originally Posted by skeeter View Post
    what does |\vec{a} \times \vec{b}| get you?
    I get
    a x b = 5i - 4j - 7k
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    Quote Originally Posted by henrymath View Post
    I get
    a x b = 5i - 4j - 7k
    the magnitude of the cross product of two vectors is the area of the parallelogram formed with the two vectors as adjacent sides.

    triangle area = 1/2 parallelogram area
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    Quote Originally Posted by skeeter View Post
    the magnitude of the cross product of two vectors is the area of the parallelogram formed with the two vectors as adjacent sides.

    triangle area = 1/2 parallelogram area
    Thanks. my answer was 1/2 sqrt 90.
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