"Special Parallelogram" PPT Courseware 4

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"Special Parallelogram" PPT Courseware 4

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Definition: A parallelogram with one right angle is called a rectangle.

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It is known that △ABC is Rt△, ∠ABC=Rt∠, and BD is the midline on the hypotenuse AC

1. If BD=3cm, then AC=________cm

2 If ∠C=30°, AB=5cm, then AC=_______cm,

BD=_______cm, ∠BDC=_______

Do you know how to determine whether a parallelogram is a rectangle?

Definition of rectangle:

A parallelogram with one right angle is a rectangle.

□ABCD

∠A=900

Quadrilateral ABCD is a rectangle

Rectangular determination method 1:

A quadrilateral with three right angles is a rectangle.

Geometry language:

∵ ∠A=∠B=∠C=90°

∴ Quadrilateral ABCD is a rectangle

Rectangular determination method 2:

A parallelogram with equal diagonals is a rectangle.

(A quadrilateral with equal diagonals that bisect each other is a rectangle.)

Geometry language:

∵ Quadrilateral ABCD is a parallelogram

AC=BD

(or OA=OC=OB=OD)

∴ Quadrilateral ABCD is a rectangle

1. Among the following conditions, which one cannot determine that quadrilateral ABCD is a rectangle ( ).

A． AB∥CD, AB=CD, AC=BD

B． ∠A=∠B=∠D=90°

C. AB=BC, AD=CD, and ∠C=90°

D. AB=CD, AD=BC, ∠A=90°

2. Which of the following statements is wrong ( )

A. A parallelogram with one interior angle that is a right angle is a rectangle

B. The four corners of a rectangle are all right angles, and the diagonals are equal

C. A parallelogram with equal diagonals is a rectangle

D. A quadrilateral with two right angles is a rectangle

Summary: How to determine a rectangle

method 1:

A parallelogram with one right angle is a rectangle.

Method 2:

A parallelogram with equal diagonals is a rectangle.

(A quadrilateral with equal diagonals that bisect each other is a rectangle.)

Method 3:

A quadrilateral with three right angles is a rectangle.

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"Special Parallelograms" PPT courseware 6:

"Special Parallelogram" PPT Courseware 6 Creation Scenario 1 The square is a special rhombus Scenario 2 Questions: 1. When the CD in the picture is translated, what kind of shape does this shape always look like? 2. When CD moves to the CD position, and AD=AB, is the quadrilateral ABCD still a rectangle?

"Special Parallelograms" PPT courseware 5:

"Special Parallelograms" PPT Courseware 5 Scenario Creation We have studied parallelograms and rectangles before, and we know what shape it will become if one of the angles of a parallelogram is a right angle? (A rectangle is obtained by changing the angle) If the parallelogram is transformed from the angle of the side special..

"Special Parallelograms" PPT courseware 3:

"Special Parallelograms" PPT Courseware 3 Review Questions 1. What is a parallelogram? 2. What is the relationship between parallelograms and quadrilaterals? 3. What are the properties of parallelograms? ① Sides: Opposite sides are parallel and equal. ② Angle: Opposite angles are equal and adjacent angles are complementary. ③ Opposite angles..

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Update Time: 2024-11-25

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