Name, measure, and classify angles

Learning Objectives Identify the vertex and rays that form an angle. Correctly name an angle using three points or by its vertex. Use a protractor to measure angles accurately to the nearest degree. Classify angles as acute, right, obtuse, or straight based on their measure. Define and identify complementary, supplementary, and vertical angles. Solve for an unknown angle measure using the properties of complementary, supplementary, and vertical angles. Have you ever wondered what makes a perfect skateboard ramp launch or how a pizza is cut into equal slices? 🍕 It's all about angles! In this tutorial, you will learn the fundamental skills of working with angles. We will explore how to name them, measure them precisely with a tool called a protractor, and classify them...

TermDefinitionExample AngleAn angle is a figure formed by two rays sharing a common endpoint, called the vertex.The corner of a square is an angle. The two sides of the square that meet at the corner are the rays, and the corner point itself is the vertex. VertexThe common endpoint where the two rays of an angle meet.If an angle is named ∠ABC, the vertex is point B. Degree (°)The standard unit used to measure angles. A full circle is divided into 360 degrees.A right angle measures exactly 90°. ProtractorA semi-circular tool used for measuring the size of an angle in degrees.To measure an angle, you align the protractor's baseline with one ray and its center point on the vertex. Acute AngleAn angle that measures less than 90°.An angle measuring 45° is an acute angle. Obtuse AngleAn an...

Complementary Angles m\angle A + m\angle B = 90° Two angles are complementary if the sum of their measures is 90°. They do not have to be adjacent (next to each other). Supplementary Angles m\angle A + m\angle B = 180° Two angles are supplementary if the sum of their measures is 180°. If they are adjacent, they form a straight line. Vertical Angles m\angle A = m\angle C and m\angle B = m\angle D When two lines intersect, they form two pairs of opposite angles called vertical angles. Vertical angles are always congruent (equal in measure).