Question

If the opposite corners of the rectangle ABCD are A (5, 3) and C (10, 1) and the equation of side BC is x-2y=8, find the equations of the other three sides. You must show your work and explain why you are doing it. (Note: opposite side of a rectangle are parallel and consecutive sides are

perpendicular)

Answer 1

Equation of side AB:

We know the coordinates of A and B, so we can use the point-slope form to create the equation of the line:

y - 3 = (3/5)(x - 5)

y - 3 = 3/5x - 15/5

5/3y - 15/3 = x - 5

5/3y - x = -15/3 + 5

5/3y - x + 15/3 = 5

5/3y - x + 15/3 = 0

Equation of side AB: 5/3y - x + 15/3 = 0

Equation of side DC:

We know the coordinates of C and D, so we can use the point-slope form to create the equation of the line:

y - 1 = (2/5)(x - 10)

y - 1 = 2/5x - 20/5

5/2y - 10 = x - 10

5/2y - x = -10

5/2y - x - 10 = 0

Equation of side DC: 5/2y - x - 10 = 0

Equation of side BD:

We know the equation of side BC (x - 2y = 8) and that consecutive sides are perpendicular, so we can use the slope-intercept form to find the equation of line BD:

Slope of BC = -2/1

Slope of BD = -1/-2 = 1/2

y = (1/2)x + b

We can use the coordinates of B to find b:

1 = (1/2)(8) + b

2 = 4 + b

b = -2

Equation of side BD: y = (1/2)x - 2

Explanation: