Download Classify Triangles- Sides and Angles


Triangle Song - YouTube
Triangles

A triangle is a 3sided polygon.
Every triangle has
three sides and
three angles. When
added together, the
three angles equal
180°.
Acute Triangles
An acute has three
angles that are less
than 90°.
 Remember AAAA.
 ALL ANGLES ARE
ACUTE!

Obtuse Triangles

An obtuse triangle is a
triangle in which one of
the angles is greater than
90° and the other two
angles are acute.

One obtuse angle and
Two acute angles
Right Triangles

A right triangle is
triangle with an
angle of 90°.

One right angle and
two acute angles
Scalene Triangles

A triangle with
three unequal
sides.

The “mean
scalene” doesn’t
want to get along.
All of the sides are
different lengths!
Isosceles Triangles
An isosceles triangle is a triangle with
two equal sides.
When two sides are the same we call
them CONGRUENT.

To remember this triangle…..
“eye” …soceles” It will remind me
that I have 2 eyes. The “e-l-e-s” at the
end is close to how we spell the word
eyes.

An isosceles triangle has 2 sides that
are the same (equal in length).
It has at least 2 acute angles.

Equilateral Triangles



An equilateral
triangle is a triangle
with all three sides of
equal length
All the angles will be
the same size
(acute).
Equilateral you are
so fine, all your sides
are the same size!
Triangle Quiz

Please complete the following quiz that
covers the information that was just
presented to you.
Question 1

If a triangle has
three unequal sides
it is a ______
triangle.
 A) Scalene
 B) Obtuse
 C) Isosceles

Answer:
 A) Scalene
Question 2

A triangle which has
three equal sides is
a ______ triangle.
 A) Acute
 B) Equilateral
 C)Scalene

Answer:
 C) Equilateral
Question 3

A triangle with (at
least) two equal
sides is a ______
triangle.
 A) Scalene
 B) Isosceles
 C) Congruent

Answer:
 B) Isosceles
Question 4

Two triangles that
are equal are called
______ triangles
 A) Acute
 B) Obtuse
 C) Congruent

Answer:
 C) Congruent
Question 5

A triangle with all
three sides of equal
length is a ______
triangle.
 A) Equilateral
 B) Right
 C) Equiangular

Answer:
 A) Equilateral
Question 6

A triangle with an
angle of 90° is a
______ triangle.
 A) Acute
 B) Right
 C) Congruent

Answer:
 B) Right
Question 7

A triangle in which
all three angles are
less than 90° is a
______ triangle.
 A) Right
 B) Acute
 C) Scalene

Answer:
 B) Acute
Question 8

A triangle in which
one of the angles is
greater than 90° is a
______ triangle.
 A) Obtuse
 B) Isosceles
 C) Acute

Answer:
 A) Obtuse

http://www.aaamath.com/geo318triangle-angles.html