Question

In the coordinate plane, draw quadrilateral ABCD with A(–5, 0), B(2, –6), C(8, 1), and D(1, 7), then demonstrate that ABCD is a rectangle.

Answer 1

ABCD is a rectangle

Explanation:

∵ A = (-5 , 0) , B = (2 , -6) , C = (8 , 1) , D = (1 , 7)

∵ The x-coordinate of the mid-point of AC = (-5 + 8)/2 =3/2

∵ The y-coordinate of the mid-point of AC = (0 + 1)/2 = 1/2

∴ The mid-point of AC = (3/2 , 1/2)

∵ The x-coordinate of the mid-point of BD = (2 + 1)/2 =3/2

∵ The y-coordinate of the mid-point of BD = (-6 + 7)/2 = 1/2

∴ The mid-point of BD = (3/2 , 1/2)

∴ The mid-point of AC = The mid-point of BD ⇒ (1)

∵ AC = √[(8 - -5)²+(1 - 0)² = √170

∵ BD = √[(1 - 2)²+(7 - -6)² = √170

∴ AC = BD ⇒ (2)

From (1) and (2)

AC and BD equal each other and bisects each other

∴ ABCD is a rectangle