To prove that quadrilateral ABCD is a parallelogram, Valentina needs to establish several key pieces of information. Here are the essential steps she should consider:
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Show that opposite sides are equal: Valentina can show that lengths of sides AB and CD are equal, as well as lengths of sides AD and BC. For example:
- Calculate the lengths of segments AB and CD:
- Length of AB = √((4-3)² + (5-2)²) = √(1 + 9) = √10.
- Length of CD = √((10-9)² + (5-2)²) = √(1 + 9) = √10.
- Since both lengths are equal, this indicates that AB is parallel and equal in length to CD.
- Calculate the lengths of segments AB and CD:
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Show that the diagonals bisect each other: Valentina can utilize points E, the midpoint of diagonals AC and BD:
- Calculate the midpoints of AC and BD to show they are the same.
- Midpoint of AC = ((3 + 10)/2, (2 + 5)/2) = (6.5, 3.5).
- Midpoint of BD = ((4 + 9)/2, (5 + 2)/2) = (6.5, 3.5).
- Since the midpoints are equal, it shows that the diagonals bisect each other, which is a property of parallelograms.
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Show that opposite sides are parallel: Valentina can determine the slopes of sides AD and BC:
- Calculate the slope of AD:
- Slope of AD = (2 - 5)/(3 - 9) = -3/-6 = 0.5.
- Calculate the slope of BC:
- Slope of BC = (5 - 2)/(4 - 10) = 3/-6 = -0.5.
- Since the slopes are negative reciprocals of each other, this establishes that AD is parallel to BC.
- Calculate the slope of AD:
With this information, Valentina can conclude that ABCD is a parallelogram.
Summary of Needed Information:
- To show that opposite sides AB and CD (and also AD and BC) are equal in length.
- To demonstrate that points E serves as the midpoint of diagonals AC and BD, proving that those diagonals bisect each other.
- To verify that opposite sides AD and BC are parallel.
None of the additional information about specific distances associated with segment CE and segment DE is necessary provided the main criteria for proving ABCD is a parallelogram are satisfied.