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Math Help - triangle vertices

  1. #1
    Senior Member
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    triangle vertices

    FInd the area of the triangle whose verices are P(1, 1, -1), Q(1, -1, 1) and R(-1, 1, 1)

    really need some help find the area for this problem please.
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  2. #2
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    Hello, rcmango!

    FInd the area of the triangle whose verices are: P(1,1,-1), Q(1,-1,1), R(-1,1,1)

    The "symmetry" of the coordinates made me suspicious. . ._
    I found the lengths of the sides to be: PQ = QR = RP = 2√2
    . . It's an equilateral triangle!

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _
    The area of an equilateral triangle of side x is: .A .= .(√3/4)x

    . . . . . . . . . . . . . . . . _ . . . . _ . . - - . ._
    Therefore: .Area .= .(√3/4)(2√2) .= .2√3

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