Chapter 5: Quadrilaterals Chapter 5: Quadrilaterals 5-1: Parallelograms

Review of quadrilaterals What is a quadrilateral? What is the sum of the interior angles for a quadrilateral? What are some quadrilaterals with special names?

What is a regular quadrilateral better known as? What is a regular quadrilateral better known as?

Parallelograms Definition Definition a quadrilateral with both pairs of opposite sides parallel We write it as ABCD (go clockwise).

Opposite sides of a parallelogram are congruent. Theorem 5-1 Opposite sides of a parallelogram are congruent.

Opposite angles of a parallelogram are congruent. Theorem 5-2 Opposite angles of a parallelogram are congruent.

Diagonals of a parallelogram bisect each other. Theorem 5-3 Diagonals of a parallelogram bisect each other. Diagonals of a parallelogram create congruent triangles.

What kind of special angles are A & B? What kind of special angles are B & C? A B D C In a parallelogram, consecutive angles are___, while opposite angles are___.

If LMNO is a parallelogram, then find a, b, x, & y a 45 ° y = a = b = x = b 9 12 35 x y M N L O y = a = b = x = b a 6 8 80 ° x y M N L O

Find x & y for PINE y = x = I P E N y = x = I P E N 11x (4y+5) 18 22 22 18 y = x = 2x+8 (4y-2) I P E N 45 ° y = x = 80 11x (4y+5) I P E N

Find the perimeter of PINE, if PI=13 & IN = 18 Find the perimeter of PINE, if PI=13 & IN = 18 Find x & y for PINE P 4x-3y I 2x-y 5 E N 9 x = y =

True or False Every parallelogram is a quadrilateral. Every parallelogram is a quadrilateral. Every quadrilateral is a parallelogram. All angles of a parallelogram are congruent. All sides of a parallelogram are congruent. In RSTU, . In ABCD, if In WXYZ, In ABCD,

Can you name 6 properties (actually, 5 properties and one definition) of parallelograms?

Section 5.1 Classroom Exercises (p. 168) #3-8 & 16 Homework Section 5.1 Classroom Exercises (p. 168) #3-8 & 16 Section 5.1 Written Exercises (p. 169-170) #5-12, 16, & 19-30