6th A and 6th B

Goal: Classify triangles by their sides and by their measures.

A triangle is a polygon with three angles and three sides.

Triangles can be classified according to their lengths of their sides:

• Scalene triangles: all sides have different lengths.
• Equilateral triangles: all sides have the same lengths.
• Isosceles triangles: two sides have the same lengths.

Triangles can be classified according to their angles:

• Acute triangles: all angles are acute; that is, less than 90.
• Right triangles: one angle is right; that is, 90.
• Obtuse triangles: one angle is obtuse; that is more than 90.

Angles in a triangle: the interior angles add up to 180.

a + b + c = 180

Classwork:

A: p.405(1-10); p.406(17-25)

B: p.438(1-10); p.439(23-28)

Homework:

A: p.406(11-16); Reteach Workbook p.110

B: p.439(11-16)