Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
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Exercise 6 Page 425

Review the classifications of quadrilaterals.

x^(∘)=130^(∘)
y^(∘)=50^(∘)

Practice makes perfect

Let's review the classifications of quadrilaterals.

Quadrilateral Definition Properties
Parallelogram Both pairs of opposite sides are parallel.
  • Opposite sides are congruent.
  • Consecutive angles are supplementary.
  • Opposite angles are congruent.
  • Diagonals bisect each other.
Rhombus Parallelogram with four congruent sides.
  • Diagonals are perpendicular.
  • Each diagonal bisects a pair of opposite angles.
Rectangle Parallelogram with four right angles.
  • Diagonals are congruent.
Isosceles trapezoid Trapezoid with legs that are congruent.
  • Diagonals are congruent.
  • Base angles are equal in measure.
  • Lower base angle is supplementary to the consecutive upper base angle.
Kite Quadrilateral with two pairs of consecutive congruent sides and no opposite congruent sides.
  • Diagonals are perpendicular.
Now let's take a look at the given figure.

In the given quadrilateral, exactly one pair of opposite sides is parallel. We also see that two of its sides are congruent. Therefore, the figure is an isosceles trapezoid. We know from the table that for this figure, the base angles have the same measure.

We also know that in an isosceles trapezoid, a lower base angle and its consecutive upper base angle are supplementary, meaning they add up to 180^(∘). We can use this fact to find the value of x^(∘). 50^(∘)+x^(∘)=180^(∘) ⇒ x^(∘)=130^(∘) We found that x^(∘)=130^(∘) and y^(∘)=50^(∘).