13 14

15 16

Warm UpUse the diagram below to answer the following:

1. If m<7 = 140º, determine the m<6.

2. If m<7 = 140º, determine the m<13.

3. If m<7 = 140º, determine the m<10.

4. If you know the m<7, can you find the measure of all the other “inside” angles?

Homework Check

Today’s Objectives

• Students will inspect the properties of parallelograms and use them to solve for missing parts.

Parallelograms and their properties

A quadrilateral is a Parallelogram if opposite sides are parallel

When you mark diagrams of quadrilaterals, use matching arrowheads to indicate which

sides are parallel.

The symbol PQRS is read "parallelogram PQRS."

Other Properties of a

1. Opposite sides are parallel and

2. Opposite ∠ ‘s are

3. Consecutive ∠ ‘s are supplementary (Sum to 180)

a+b = 180 b+d=180a+c=180 c+d=180

Same side interior angles

4. Diagonals bisect each other (break in half)

RectangleDefinition: a parallelogram with 4 right angles

Properties: All properties of parallelograms PLUS…– Diagonals are (RC = ET) – Diagonals create 4 isosceles triangles

A Special Parallelogram

Find the measure of the indicated

Find the measure of the indicated

Find the measure of the indicated

Example 1: ABCD is a

AB = 5x+3, DC=4x+15. Find x

Ex.3: AE=2x+5, EC=4x-9, Find AC

Ex. 4: DB=8x-4, EB=2x, Find DE