7.7.3 Triangles

Classifying Triangles Two ways: By the angle size By the side length In describing a triangle, talk about it’s angles first, then the lengths of its sides NOTE: When no measurement is given, you have to look at the symbols. If no symbols are given, the measurement is not equal. Do not assume measurements are equal simply because they look equal.

Naming Triangles by Their Angles

Triangle Names – By Angle Acute Triangle – All acute angles Obtuse Triangle – One obtuse angle Right Triangle – One right angle Equiangular Triangle – Three congruent angles

Naming Triangles By Their Sides Congruent Sides - Sides are the same length

Triangle Names – By Sides Scalene Triangle – No congruent sides Isosceles Triangle – Two congruent sides Equilateral Triangle – Three congruent sides

Naming Examples

Your Turn! Acute Triangle – All acute angles Obtuse Triangle – One obtuse angle Right Triangle – One right angle Equiangular Triangle – Three congruent angles Scalene Triangle – No congruent sides Isosceles Triangle – Two congruent sides Equilateral Triangle – Three congruent sides

Drawing a Triangle Using Angles

Drawing a Triangle Using Sides

Your Turn! Draw a triangle with angle measures of 45, 45, and 90. Then classify the triangle Draw a triangle with a 1-inch side and a 2- inch side that meet at a 60 angle. Then classify the triangle HINT: Just like when you name a triangle, start with the angle before you deal with the sides…

Homework Page 286 (#4, 5, 7, 8, 9, 11, 12, 13, 15, 18, 19)