138k views
1 vote
Plot the points A(-2,-3), B(1, 12), C(3, -4) on the coordinate axes below. State the

coordinates of point D such that A, B, C, and D would form a rectangle. (Plotting
point D is optional.)

1 Answer

2 votes

The opposite sides of the quadrilateral should be parallel and the diagonals should be equal. [For a rectangle]

First, let's find the slope of AB and its perpendicular slope.

Slope of AB = (y2 - y1)/(x2 - x1) = (12 - (-3))/(1 - (-2)) = 5

Perpendicular slope of AB = -1/5

The midpoint of AB is ((-2+1)/2, (-3+12)/2) = (-0.5, 4.5)

Let D be the point on line segment AC such that AD is perpendicular to AC. Since AB is parallel to DC, the slope of DC is also 5.

Slope of AC = (-4 - (-3))/(3 - (-2)) = -1/5

The equation of line AC is y = (-1/5)x - (13/5)

The equation of line DC passing through (3,-4) with slope 5 is y - (-4) = 5(x - 3)

Solving these two equations, we get D(2,-14/5).

Therefore, the coordinates of point D are (2, -14/5).

We can plot the points on the coordinate axes and verify that A, B, C, and D indeed form a rectangle.

User Jleft
by
8.6k points