Question

Without distance formula, show that the points P(2,1), Q(-1,-5), R(1,5) and S(-2,-1) form a parallelogram.

Answer 1

Slope of PQ = `(-5 - 1)/(-1 -2)` = 2

Slope of RS = `(5 + 1)/(1 + 2)` = 2

Slope of PQ = Slope of RS

`therefore` PQ ll RS

Also,slope of QR = `(5 + 5)/(1 + 1) = 5`

Slope of SP = `(-1 - 19)/(-2 -2) = 5`

Slope of QR = Slope of SP

`therefore` QR ll SP