Download Triangles

Triangles Galore!
Classification By Angle
• Acute triangle
• Obtuse triangle
• Right triangle
Acute Triangles
• An acute triangle has only acute angles.
• What could another combination of angles be
for an acute triangle?
Obtuse triangle
• An obtuse triangle has one obtuse angle.
• Can a triangle have more than two obtuse
angles?
Right Triangle
• A right triangle has only one right angle.
• Can a right triangle also be an acute triangle?
180o
• When you add all the angles of any triangle
they add up to 1800.
• We proved this in yesterdays lab! Tear the
corners off of a triangle, connect them
together using their smooth sides and see
what it makes.
Find the unknown angle then classify it.
60
60
60
Classification by Sides
• Equilateral triangle
• Isosceles triangle
• Scalene triangle
What does it mean to be congruent?
Sides of a shape are congruent if they are the
same length.
You can use tick marks to show congruent
sides.
Scalene Triangle
• A scalene triangle has no congruent sides.
• If a triangle has no congruent sides, what do
you know about it’s angle measurements?
Isosceles Triangle
• An isosceles triangle has at least two
congruent sides.
• Can a right triangle also be isosceles?
Equilateral Triangle
• An equilateral triangle has three congruent
sides.
• Draw an example of an equilateral triangle
and label the side measurements.
Let’s Classify!
Classify the triangles by there angles and sides.
1.
2.
3.
Try this one!
• The perimeter of the triangle is 24 cm.
Classify the triangle.
8
8
Try this one!
• The perimeter of the triangle is 30 ft. Classify
the triangle.
6ft.
12 ft.