Question

If ( -1, 2 ) , ( 2, -1 ), and ( 3, 1) are any three vertices of a parallelogram, then

Answer 1

Answer:

(- 2, 0)

Step-by-step explanation:

Slopes of 2 parallel lines are the same. Let's find slope "m" of line going through (2, -1) and (3, 1)  

m = (1 - (- 1)) ÷ (3 - 2) = 2

y - 2 = 2(x - (- 1))

y = 2x + 4  ..... (1)

Let's find slope "m" of line going through (- 1, 2) and (3, 1)

m = (1 - 2) / (3 - (- 1)) = - 1 / 4

y - (- 1)  = (- 1/4)(x - 2)

y = (- 1/4)x - 1/2   ..... (2)

Equations (1) and (2) intersept in the point:

2x + (1/4)x = - 4 - 1/2

x = - 2

y = 0