"Understanding of Parallelograms" PPT courseware on parallelograms and trapezoids

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"Understanding of Parallelograms" PPT courseware on parallelograms and trapezoids

Part 1: Importing new lessons

1. Jigsaw puzzle: Triangular board is our common learning tool, you can use it

Do two identical triangles form different shapes? Come and give it a try with two people.

Answer: Triangle, square, rectangle, parallelogram.

2. Reveal the topic: Today we will specifically study parallelograms.

PPT on understanding parallelograms, part 2: cooperative exploration

(1) Find parallelograms in life.

Can you find the parallelogram in the picture?

(2) Observe and guess the characteristics of parallelograms

Question: Think about the characteristics of parallelograms? After thinking about it, talk to your classmates.

Answer: There are four sides, the opposite sides are equal in length, parallel, and the opposite angles are equal.

(3) Base and height of parallelogram

(4) Characteristics of parallelograms

1. Parallelogram is unstable

2. The rectangle is a special one among so many parallelograms. We also say that the rectangle is a special parallelogram.

Class summary

What did you gain from this class? Is there anything else you don’t understand?

Answer: Opposite sides are equal Opposite sides are parallel

PPT on understanding parallelograms, part three: knowledge sorting

1. Characteristics of parallelogram:

A quadrilateral with two opposite sides that are parallel is a parallelogram.

Rectangles and squares are special parallelograms.

2. How to draw the height of a parallelogram. (As shown in the picture)

[Method summary] Draw a vertical line from one point on one side of the parallel line to the opposite side. The line segment between this point and the vertical foot is the height of the parallelogram. This opposite side is called the base. Parallelograms can have heights of two lengths. From any point on one side, you can draw heights to its opposite side, and you can draw countless heights.

3. Drawing a height is equivalent to drawing a perpendicular to a known straight line through a point outside the straight line. The line segment between this point and the vertical foot is the height of the figure. Pay attention to three points when painting:

(1) The height is represented by a dotted line;

(2) Be sure to draw the vertical foot symbol;

(3) The height and base drawn should correspond.

4. Parallelograms are easy to deform. Lifting racks, electric sliding doors, etc. are made using this feature in daily life.

PPT on understanding parallelograms, part 4: analysis of examples

Example 1: Which of the following figures are parallelograms? Draw two different heights for each parallelogram.

[Analysis] This question tests the height of a parallelogram. First, based on the characteristics of parallelograms that opposite sides are parallel and equal, it can be judged that Figures 1 and 3 conform to the characteristics of parallelograms that opposite sides are parallel and equal, so these two figures are parallelograms. (drawing sketch)

In the figure below, which line segment is the height of sides AB and BC?

Answer tip: The height of side AB is CE, and the height of side BC is AF.

Example 2 Judgment: A parallelogram can be formed using four 6 cm rods.

[Analysis] This question is correct. Opposite sides of a parallelogram are equal and parallel.

A figure made of four 6 cm long sticks has four equal sides, and of course the opposite sides are equal to each other.

judge.

(1) Use two small rods of 4 cm and two of 5 cm to form a parallelogram. ( )

(2) The opposite sides of a parallelogram are equal, and the four sides cannot be equal. ( )

PPT on understanding parallelograms, Part 5: Classwork

1. Judgment. (In the brackets, put “√” if the answer is correct and “×” if the answer is wrong)

(1) A rectangle is a special parallelogram. ( )

(2) Parallelograms are very stable, so the stairs create a parallelogram shape. ( )

(3) Countless heights can be drawn from one vertex of a parallelogram to the opposite side. ( )

(4) Use two 8 cm and two 6 cm small rods to form a parallelogram. ( )

2. Picture recognition questions.

(1) Fill in the number of the parallelogram in the brackets.

The parallelogram has ( ).

(2) Based on the marked base of each figure below, draw the height of the figure.

3. What is the height of the parallelogram below through point A? How many can you draw?

Answer: two

4. There are ( ) triangles and ( ) parallelograms in the picture.

5. First draw a triangle, then add two line segments to make it a parallelogram.

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For more information about the PPT courseware "Understanding of Parallelograms and Trapezoidal Parallelograms", please click on the PPT tag of "Understanding of Parallelograms and Trapezoidal Parallelograms".

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Update Time: 2024-09-08

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