Upload
maria-lee
View
215
Download
1
Tags:
Embed Size (px)
Citation preview
Unit 6: Geometry
Minds On
• Draw a triangle on a blank piece of paper
• Measure all interior angles• Measure all exterior angles• Make conclusions about the interior
and exterior angles of a triangle
Make a Triangle!
Unit 6: Geometry
Lesson Two: Triangle and Other Polygon Angles
Learning Goals
I can describe the relationship between the exterior and interior angles of a triangle and use these relationships to find missing angle measurement
Unit 6: GeometryLesson Two: Triangle and Other Polygon
AnglesVocabularyVertex – Where two line segments join or meet.
Polygon – a two-dimensional shape made of 3 or more lines that join together to make a closed loop.
Interior Angle – The angle formed inside a polygon by two sides meeting at a vertex.
Exterior Angle – The angle formed at the vertex by one side of a polygon that has been extended through the vertex, and an original side.
Unit 6: Geometry
Lesson Two: Triangle and Other Polygon Angles
1. The interior angles of a triangle add up to 1802. The exterior angles of a triangle add up to 3603. The value of an exterior angle is equal to the
sum of the two interior angles at the opposite vertices.
We call them the Remote Interior Angles.
Unit 6: Geometry
Learning Goals
I can determine the sum of interior and exterior angles of various regular polygons
I can use the properties of polygons to find unknown side lengths and missing angle measurements.
Lesson Two: Triangle and Other Polygon Angles
Unit 6: Geometry
Vocabulary
Regular Polygon: a polygon that has equal side lengths and equal interior angles. (An equilateral triangle is an example)
Lesson Two: Triangle and Other Polygon Angles
Unit 6: Geometry
General rule for polygon angles:
In polygon with n sides:• the sum of the interior angles is 180(n – 2)° • the sum of the exterior angles is 360°
WHY??
Lesson Two: Triangle and Other Polygon Angles
Unit 6: Geometry
Example 2: Determine the value of and the value of each angle:
Lesson Two: Triangle and Other Polygon Angles
Unit 6: Geometry
Example 3: Determine the value of the interior and exterior angles for this decagon.(Hint, this is a regular polygon)
Lesson Two: Triangle and Other Polygon Angles