Lesson 4 Notes
A triangle is a closed figure consisting of three line segments that intersect only at their endpoints.
Classifying Triangles by their Angles
A right triangle has one right angle.
An acute triangle has three acute angles.
An obtuse triangle has one obtuse angle and two acute angles.
Classifying Triangles by their Sides
An equilateral triangle has three congruent sides.
An isosceles triangle has two congruent sides.
A scalene triangle has no congruent sides.
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