Q23 of 169 Page 656

If θ is the angle between the diagonals of a parallelogram ABCD whose vertices are A(0, 2), B(2,-1), C(4,

Given points of the parallelogram are A(0, 2), B(2,-1), C(4, 0) and D(2, 3)



The slope of diagonal AC =


The slope of diagonal BD =


So diagonal BD is perpendicular to X-axis. Hence it is parallel to Y-axis.


Product of slope of two diagonals is equal to -1.





Hence proved.


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