13. (a) Let ABCD be a quadrilateral whose vertices are (6,8), (3,7), (-2,-2) and (1, -1) respectively.
Prove that ABCD is a parallelogram. Is it a rectangle?
Answers
Given : ABCD be a quadrilateral whose vertices are (6,8), (3,7), (-2,-2) and (1, -1) respectively.
To Find : Prove that ABCD is a parallelogram
Is it a rectangle?
Solution:
A (6,8), B (3,7), C (-2,-2) and D (1, -1)
Slope of AB = ( 7 - 8)/(3 - 6) = 1/3
Slope of CD = ( -1 - (-2))/(1 -(-2)) = 1/3
Slope of AB = Slope of CD
=> AB || CD
Slope of BC = 9/5
Slope of AD = 9/5
=> BC || AD
AB || CD & BC || AD
Hence ABCD is a parallogram
QED
Proved
Slope of AB * Slope of BC = (1/3)(9/5) = 3/5 ≠ - 1
Hence AB & BC are not perpendicular
so ABCD is not a rectangle
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Step-by-step explanation:
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