If point A(6,1),B (8,2),C (8,4),D (p,3) are vertices of a parallelogram taken in order, find value of p
AB ∥ DC and BC ∥ AD
BC is a VERTICAL line that's parallel to the y-axis, and parallel and congruent to AD. BC's length = 4 - 2, or 2
AD is a VERTICAL line that's parallel to the y-axis, and parallel and congruent to BC. Points A and D will therefore have the SAME x-coordinate, which is 6.
Therefore, p = 6.
OR
You can also see that AB and DC are parallel, and so, have the same slope. Slope of AB =
DC's slope also = .
To find p, we get: