Pearson Geometry Common Core, 2011
PG
Pearson Geometry Common Core, 2011 View details
7. Polygons in the Coordinate Plane
Continue to next subchapter

Exercise 28 Page 404

Recall the classification of quadrilaterals. You can begin by finding the slopes of the sides.

Rectangle

Practice makes perfect

Let's plot the given points on a coordinate plane and graph the quadrilateral.

To determine the most precise name for our quadrilateral, we will review the classification of quadrilaterals.
Quadrilateral Definition
Parallelogram Both pairs of opposite sides are parallel
Rhombus Parallelogram with four congruent sides
Rectangle Parallelogram with four right angles
Square Parallelogram with four congruent sides and four right angles
Trapezoid Quadrilateral with exactly one pair of parallel sides
Isosceles Trapezoid Trapezoid with legs that are congruent
Kite Quadrilateral with two pairs of consecutive sides congruent and no opposite sides congruent

Now, we will find the slopes of the sides using the Slope Formula.

Side Slope Formula Simplified
Slope of HK: ( - 2,- 3), ( - 3,- 1) - 1-( -3)/- 3-( - 2) - 2
Slope of KJ: ( - 3,- 1), ( 3, 2) 2-( - 1)/3-( - 3) 1/2
Slope of JI: ( 3, 2), ( 4, 0) 0- 2/4- 3 - 2
Slope of IH: ( 4, 0), ( - 2,- 3) - 3- 0/- 2- 4 1/2

We can tell that the slopes of the opposite sides of our quadrilateral are equal. Therefore, both pairs of opposite sides are parallel and the quadrilateral is a parallelogram. Additionally, the consecutive sides are perpendicular, as their slopes are opposite reciprocals. - 2 * 1/2 = -1 Therefore, our parallelogram is either a rectangle or a square. To check, we can find the lengths of its sides using the Distance Formula.

Side Distance Formula Simplified
Length of HK: ( - 2,- 3), ( - 3,- 1) sqrt(( - 3-( - 2))^2+( - 1-( - 3))^2) sqrt(5)
Length of KJ: ( - 3,- 1), ( 3, 2) sqrt(( 3-( - 3))^2+( 2-( - 1))^2) sqrt(45)
Length of JI: ( 3, 2), ( 4, 0) sqrt(( 4- 3)^2+( 0- 2)^2) sqrt(5)
Length of IH: ( 4, 0), ( - 2,- 3) sqrt(( - 2- 4)^2+( - 3- 0)^2) sqrt(45)

Our parallelogram has two pairs of opposite congruent sides. Therefore, the most precise name for this quadrilateral is rectangle.