Angles

An angle is formed when two rays share a common endpoint, called the vertex. Angles are measured in degrees and are used to describe the amount of rotation between the two rays.

Types of Angles

There are several types of angles:

Acute Angle: An angle that measures less than 90 degrees.
Right Angle: An angle that measures exactly 90 degrees.
Obtuse Angle: An angle that measures more than 90 degrees but less than 180 degrees.
Straight Angle: An angle that measures exactly 180 degrees, forming a straight line.
Reflex Angle: An angle that measures more than 180 degrees but less than 360 degrees.

Measuring Angles

Angles are measured using a protractor, which is a tool with a semicircular shape and degree markings. To measure an angle:

Place the center of the protractor over the vertex of the angle.
Align one of the rays with the zero mark on the protractor.
Read the number where the other ray intersects the protractor to determine the angle measurement.

Angles in Shapes

Angles are also commonly found in geometric shapes. For example:

In a triangle, the three angles add up to 180 degrees.
In a quadrilateral, the four angles add up to 360 degrees.
In a circle, the angle formed by two radii at the center is always 90 degrees, and the angle at the circumference is half the angle at the center.

Understanding angles is important in various mathematical and real-world applications, such as geometry, architecture, and engineering.

Hopefully, this explanation helps you understand the concept of angles!

◂Math Worksheets and Study Guides Third Grade. Perimeter

The resources above cover the following skills:

Geometry (NCTM)

Analyze characteristics and properties of two- and three-dimensional geometric shapes and develop mathematical arguments about geometric relationships.

Identify, compare, and analyze attributes of two- and three-dimensional shapes and develop vocabulary to describe the attributes.

Use visualization, spatial reasoning, and geometric modeling to solve problems.

Use geometric models to solve problems in other areas of mathematics, such as number and measurement.

Connections to the Grade 3 Focal Points (NCTM)

Measurement: Students in grade 3 strengthen their understanding of fractions as they confront problems in linear measurement that call for more precision than the whole unit allowed them in their work in grade 2. They develop their facility in measuring with fractional parts of linear units. Students develop measurement concepts and skills through experiences in analyzing attributes and properties of two-dimensional objects. They form an understanding of perimeter as a measurable attribute and select appropriate units, strategies, and tools to solve problems involving perimeter.