SOLUTION: Always, sometimes, or never; If the opposite angles of a quadrilateral are supplementary, the quadrilateral is a parallelogram

Question 242792: Always, sometimes, or never; If the opposite angles of a quadrilateral are supplementary, the quadrilateral is a parallelogram
Answer by Edwin McCravy(20077) (Show Source): You can put this solution on YOUR website!
Always, sometimes, or never; If the opposite angles of a quadrilateral are supplementary, the quadrilateral is a parallelogram.

When and only when the quadrilateral is a parallelogram which is also 
a rectangle and the opposite angles are both 90�. Two right angles
are supplementary.



So the answer is "sometimes".

Edwin

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