6 * 4 Special Parallelograms

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L.E.Q. How do you use properties of diagonals of rhombuses and rectangles and determine whether a parallelogram is a rhombus or a rectangle?

Each diagonal of a rhombus bisects two angles of the rhombus.

The diagonals of a rhombus are perpendicular.

MNPQ is a rhombus and m

N

120 .

Find the measure of the numbered angles.

Find the measures of the numbered angles in the rhombus below.

The diagonals of a rectangle are congruent.

Find the length of the diagonals of rectangle

GFED if FD = 2y + 4 and GE = 6y – 5.

Find the length of the diagonals of

GFED

if

FD

= 5

y

- 9 and

GE

=

y

+ 5.

If one diagonal of a parallelogram bisects two angles of the parallelogram, then the parallelogram is a rhombus.

If the diagonals of a parallelogram are perpendicular, then the parallelogram is a rhombus.

If the diagonals of a parallelogram are congruent, then the parallelogram is a rectangle.

Determine whether the quadrilateral can be a parallelogram. If not, write impossible. Explain.

◦ The quadrilateral has congruent diagonals and one angle of 60 degrees.

◦ The quadrilateral has perpendicular diagonals and four right angles.

A diagonal of a parallelogram bisects two angles of the parallelogram. Is it possible for the parallelogram to have sides of lengths 5,

6, 5, and 6? Explain.

Community Service Builders use properties of diagonals to “square up” rectangular shapes like building frames and playing-field boundaries. Suppose you are on the volunteer building team at the right. You are helping to lay out a rectangular patio. Explain how to use properties of diagonals to locate the four corners.

Pgs. 315-317 #s 2 – 20 even, 48 – 50 all.

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