3.5 What Are Special Parallelograms? Pg. 20 Properties of Rhombi, Rectangles, and Squares

3.5 – What Are Special Parallelograms?___ Properties of Rhombi, Rectangles, and Squares In the previous lesson, you learned that parallelograms have both pairs of opposite sides parallel. You also discovered many different properties of parallelograms. Today you are going to continue your investigation with parallelograms with even more special properties.

3.28 –PARALLELOGRAMS WITH RIGHT ANGLES Mark's favorite shape is a parallelogram with four right angles. a. What is the name of Mark's shape? Draw a picture to support your answer. rectangle

b. What do you already know about this shape since it is a parallelogram? Both _____________ sides are ________________ opposite parallel

Both _____________ sides are ________________ opposite congruent

Both _____________ angles are ________________ opposite congruent

Both _____________ angles are ________________ consecutive supplementary

The diagonals ________________ each other bisect

c. Mark wanted to learn more about his shape. He noticed that the diagonals seem to have a special relationship beyond just being bisected. He decided to investigate. He drew a rectangle twice, adding one diagonal. Find the length of AC and BD. Show all work. What do you notice?

= x = x 2 17 = x

= x = x 2 17 = x Diagonals are congruent

3.29 –PARALLELOGRAMS WITH EQUAL SIDES Audrey has a favorite quadrilateral is a parallelogram that has four equal sides. a. What is the name of Audrey's shape? Draw a picture to support your answer. Rhombus

b. What do you already know about this shape since it is a parallelogram? Both _____________ sides are ________________ opposite parallel

Both _____________ sides are ________________ opposite congruent

Both _____________ angles are ________________ opposite congruent

Both _____________ angles are ________________ consecutive supplementary x y xy

The diagonals ________________ each other bisect

c. Audrey wanted to learn more about her shape. She noticed that the diagonals seem to have a special relationship as well. She measured the sides of the rhombus and all were 5 units long. Then she measured AC = 6 units and BD = 8 units. Mark these lengths on the picture below. Is there a way to tell if ∆AEB is a right triangle? Explain.

= = = 25 The diagonals are perpendicular

d. Audrey noticed something else with the angle in the rhombus. Using the given lines symmetry, mark any angles congruent. What do you notice?

Diagonals bisect the angles

3.30 –PARALLELOGRAMS WITH EQUAL SIDES AND RIGHT ANGLES Ms. Matthews has a favorite quadrilateral is a parallelogram that has four right angles and four equal sides. a. What is the name of Ms. Matthews' shape? Draw a picture to support your answer. square

b. A square has more properties than any other quadrilateral. Why do you think this is? It is a parallelogram, a rectangle, and a rhombus

3.31 – SPECIAL PARALLELOGRAMS Name the type of parallelogram. Explain how you know using only the markings.

rhombusrectangle rhombus

parallelogramrectangle square

3.32 – MISSING PARTS Find the missing information based on the type of shape and its special properties.

a. The diagonals of rhombus PQRS intersect at T. Find the indicated measure. _____ _________ RP = _________ SP = _________ RS = _________ 15 30° 90° 60° 12 15

b. The diagonals of rectangle WXYZ intersect at P. Given that XZ = 12, find the indicated measure. _________ _________ _________ WP = _________ 40° 50° 80° 6

c. The diagonals of square DEFG intersect at H. Given that EH = 5, find the indicated measure. HF = 90° 45° 5