Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
Chapter Review
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Exercise 42 Page 424

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

Rhombus

Practice makes perfect

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

Let's determine the most precise name for our quadrilateral.

Name

To determine the most precise name for our quadrilateral, let's 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, let's find the slopes of the sides using the Slope Formula.

Side Slope Formula Simplified
Slope of QU: ( 4,5), ( 12,14) 14- 5/12- 4 9/8
Slope of UA: ( 12,14), ( 20, 5) 5- 14/20- 12 - 9/8
Slope of AD: ( 20, 5), ( 12, -4) -4- 5/12- 20 9/8
Slope of DQ: ( 12, -4), ( 4,5) 5-( -4)/4- 12 - 9/8

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. Let's multiply the slopes of two consecutive sides 9/8 ( - 9/8 ) = - 81/64 Since the product is - 8164≠ - 1 the sides are not opposite reciprocals. Therefore, the quadrilateral is either a parallelogram or a rhombus. To check, we can find the lengths of its sides using the Distance Formula.

Side Distance Formula Simplified
Length of QU: ( 4,5), ( 12,14) sqrt(( 12- 4)^2+( 14- 5)^2) sqrt(145)
Length of UA: ( 12,14), ( 20, 5) sqrt(( 20- 12)^2+( 5- 14)^2) sqrt(145)
Length of AD: ( 20, 5), ( 12, -4) sqrt(( 12- 20)^2+( -4- 5)^2) sqrt(145)
Length of DQ: ( 12, -4), ( 4,5) sqrt(( 4- 12)^2+( 5-( -4))^2) sqrt(145)

Our parallelogram has four congruent sides. Therefore, the most precise name for this quadrilateral is a rhombus.