"Polygon" PPT courseware 2

Description

"Polygon" PPT courseware 2

The sum of the interior angles of a pentagon = 3 × 180° = 540°

Summary: Formula for sum of interior angles of n-sided polygons

The sum of the interior angles of an n-sided polygon = (n-2) ·180°

Reflection: How do we find the sum of the interior angles of a polygon?

It is to divide a polygon into several triangles starting from a vertex of the polygon.

practice

1. The sum of the interior angles of a dodecagon is ( ).

2. When the number of sides of a polygon increases by 1, the sum of its interior angles increases ( ).

3. If the sum of the interior angles of a polygon is 720º, then the polygon has ( ) interior angles.

4. If the sum of the interior angles of a polygon is 1440 degrees, then it is a ( ) polygon.

Example 1 As shown in the figure, take an exterior angle at each vertex of the pentagon. The sum of these exterior angles is called the sum of the exterior angles of the pentagon. What is the sum of the exterior angles of a pentagon?

1. What is the relationship between any exterior angle and its adjacent interior angle?

2. What is the sum of the five exterior angles plus their five adjacent interior angles?

3. What is the relationship between the sum of the five square angles and the sum of the interior and exterior angles of the pentagon?

The sum of the exterior angles of a 5-sided polygon = 5 straight angles - the sum of the interior angles of a 5-sided polygon

=5×180°-(5-2) × 180°

=360°

Conclusion: The sum of the exterior angles of a pentagon is equal to 360°

Practice in class

1. The sum of the interior angles of an n-sided polygon is equal to __________, and the sum of the interior angles of a nine-sided polygon is equal to ___________.

2. If the sum of the interior angles of a polygon is 1440 degrees, then it is a ____ polygon.

3. It is known that each interior angle of a polygon is equal to 150°. Find the number of sides of this polygon?

4. A polygon can have three diagonals from one vertex. The sum of the interior angles of this polygon is equal to ( )

A.360° B.540° C.720° D.900°

5. Given a polygon, the sum of its interior angles is equal to twice the sum of the exterior angles. Find the number of sides of this polygon?

Keywords: Polygon teaching courseware, Qingdao edition seventh grade mathematics volume 2 PPT courseware download, seventh grade mathematics slide courseware download, polygon PPT courseware download, .PPT format;

For more information about the "Polygon" PPT courseware, please click the Polygon ppt tab.

Simple European and American PPT template with blue low plane polygon background:

This is a set of simple European and American PPT templates with a blue low-plane polygon background, a total of 26 pictures; the cover of the slide template uses multiple low-plane geometric figures with superimposed effects as the PPT background image. Fill in the PPT title text in the middle. The interface design is simple and simple. PowerPo..

Red polygon background work summary plan PPT template:

This is a set of work summary plan PPT templates with a red polygon background, a total of 25 pictures; the slide template uses a combination of red triangles as the background image. Fill in the title text of the work summary plan PPT on the left side. The interface design is simple and practical. PowerPoint template content..

Fashion colorful polygon PPT template:

This is a set of general business PPT templates with fashionable colorful polygonal backgrounds, a total of 26 pictures; the slide template cover uses diagonal lines of different thicknesses and colors as the background image. Place a white translucent gray border mask in the middle and fill in the PPT title text. interface..

File Info

Update Time: 2024-08-31

This template belongs to Mathematics courseware Qingdao Edition Seventh Grade Mathematics Volume 2 industry PPT template

Preview