Lines

Lines

Learn the basics of linear geometry!!

What are lines?

Lines are everywhere! Every surface you see that is not curved creates a line. Lines, in 2D geometry help to decode shapes and other stuff.

Linear Figures

We will learn about the basic features of each of the linear figures (mostly shapes).

Polygons

Polygons are figures or shapes that are not curved or have any openings. Some examples include pentagons, squares, or trapezoids. As you probably know, it is impossible to make a polygon with less than 3 sides. A figure with 2 sides would NOT be a polygon.

Degrees of an Angle

This is how big an angle is. There are 360 degrees in a full circle. This concept will help you understand the triangles later on in these slides.

Complementary vs Supplementary Angles

When two neighboring angles (which means they both share a side and are touching) add up to 90* together, they are complementary. When two neighboring angles add up to 180* together, they are supplementary. Look at the image on the next slide for more help.

Dont worry about the vertical and adjacent angles, we will cover that much later. Look at the supplementary and complementary.

Interior vs Exterior Angles

The angles inside the triangles are called INTERIOR angles. The angles SUPPLEMENTARY to each INTERIOR angle is called an EXTERIOR angle. The picture will help you understand.

Multiple Choice

What is a triangle?

• A polygon with 3 sides

• A polygon with 4 sides

• A non-polygon with 3 sides

• A non-polygon with 4 sides

Triangles

Triangles are 3-sided polygons. This means that they have 3 sides, no curve, and are closed (no gap) figures. They have 3 vertices (tips where the 2 sides meet) and 3 angles (inside intersections made by two sides). An interesting property of triangles is that all 3 angles' measure add up to 180*. This is called THE TRIANGLE SUM THEOREM. In any shape (not just triangles), the interior and exterior angles add up to 180*. This means that they are supplementary (you learned about these on Slide 6).

A really famous triangle property

Lets start with a triangle called "ABC". Let's take an exterior angle of interior angle C. This exterior angle is equal to the number of degrees of A+B. Look at the image for more context. Another way to write it would be to say an exterior angle is equal to two opposite interior angles.

I think you're ready to practice!!! Go to the link below!!!

https://quizizz.com/join?gc=34474348