6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral...

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6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can decide whether a quadrilateral is a parallelogram if its sides, angles and diagonals have certain properties

Transcript of 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral...

Page 1: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.

6-3Proving that a

Quadrilateral is a Parallelogram

Objective: To determine whether a quadrilateral is a parallelogram

Essential Understanding: You can decide whether a quadrilateral is a parallelogram if its sides, angles and diagonals have certain properties

Page 2: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.

Opposite angles are congruent

Review

Opposite sides are parallel

Opposite sides are congruent

Opposite angles are congruent

Consecutive angles are supplementary

Diagonals bisect each other

Page 3: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.

Theorems 6-9 and 6-10 are the converses of Theorems 6-4 and 6-5, respectively. They use angle relationships to conclude that a quadrilateral is a parallelogram.

Page 4: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.
Page 5: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.

Example:

For what value of y must PQRS be a parallelogram?

Step 1: Find x.

3x – 5 = 2x + 1

X – 5 = 1

X = 6

Step 2: Find y.

y = x + 2y = 6 + 2

y = 8

Page 6: 6-3 Proving that a Quadrilateral is a Parallelogram Objective: To determine whether a quadrilateral is a parallelogram Essential Understanding: You can.

and FINALLY

6-3 p. 372:7-15