Download classifying triangles by sides

CLASSIFYING TRIANGLES
BY ANGLES
Classifying Triangles by Angles
• ACUTE
• EQUIANGULAR
• OBTUSE
• RIGHT
ACUTE TRIANGLE
Interior Angle
•All interior angles are acute (or have a measure
less than 90°)
Example of Acute Triangle
•Phineas’s head is an acute triangle because all
interior angles measure less than 90°. This is easy
to remember because Phineas is a ‘cute’ character!
EQUIANGULAR TRIANGLE
Interior Angle
•All interior angles are congruent (exactly the
same measure)
•All interior angles ALWAYS measure 60° for an
equiangular triangle
Examples of Equiangular
Triangles
OBTUSE TRIANGLE
Obtuse Angle
•ONE interior angle is obtuse (or has a measure
greater than 90°)
•The other two interior angles of an obtuse
triangle ALWAYS are acute (or have a measure
less than 90°)
Example of Obtuse Triangle
•Dr. Doofenshmirtz’s head is shaped like an
obtuse triangle. This is easy to remember because
he is an obtuse character. An obtuse character is
one that is slow to learn or lacking insight.
RIGHT TRIANGLE
Right Angle
•ONE interior angle is a right angle (or has a
measure equal to 90°)
•The other two angles of a right triangle are
ALWAYS acute (have a measure less than 90°)
Example of A Right Triangle
YOU TRY
• ACUTE
• EQUIANGULAR
• OBTUSE
• RIGHT
YOU TRY
• ACUTE
• EQUIANGULAR
• OBTUSE
• RIGHT
YOU TRY
• ACUTE
• EQUIANGULAR
• OBTUSE
• RIGHT
YOU TRY
• ACUTE
• EQUIANGULAR
• OBTUSE
• RIGHT
CLASSIFYING TRIANGLES
BY SIDES
Classifying Triangles by Sides
• EQUALATERAL
• ISOSCELES
• SCALENE
EQUILATERAL TRIANGLE
•All sides are congruent (exactly the same length)
•EQUILATERAL TRIANGLES ARE ALWAYS
ALSO EQUIANGULAR
Examples of Equilateral
Triangles
ISOSCELES TRIANGLE
VERTEX
•Two sides are congruent (exactly the same
length)
•The angle between the congruent sides is called
the VERTEX ANGLE
Examples of Isosceles
Triangles
SCALENE TRIANGLE
•NO sides are congruent
Examples of Scalene
Triangles
Classifying Triangles
Angles are
classified
first by
ANGLE
And then
by SIDE
ISOSCELES
ACUTE
ACUTE ISOSCELES
Classifying Triangles
Angles are
classified
first by
ANGLE
And then
by SIDE
SCALENE
RIGHT
RIGHT SCALENE
Classifying Triangles
Angles are
classified
first by
ANGLE
And then
by SIDE
SCALENE
OBTUSE
OBTUSE SCALENE
YOU TRY
• RIGHT ISOSCELES
• RIGHT SCALENE
• ACUTE ISOSCELES
• EQUIANGULAR
EQUILATERAL
YOU TRY
• ACUTE ISOSCELES
• EQUIANGULAR
SCALENE
• OBTUSE SCALENE
• RIGHT
EQUILATERAL
YOU TRY
• ACUTE ISOSCELES
• EQUIANGULAR
EQUILATERAL
• OBTUSE SCALENE
YOU TRY
• ACUTE SCALENE
• OBTUSE SCALENE
• OBTUSE ISOSCELES
YOU TRY
Given: Triangle ABC is equiangular triangle
with side AB=3x-5 and side BC=2x-2. What
are the lengths of the 3 sides?
A
B
Step
1 35
Step
Step
Realize
an‘x’
equiangular
Step
4x into
Step
Combine
Plug2that
original
term
triangle is ALWAYS an
Solve
for to
x find
AB=BC
3x-5=2x-2
equation
equilateral triangle an
1x-5+5=-2+5
3x-5=2x-2
therefore
3x-5-2x=2x-2x-2
lengthALL sides are
CONGRUENT.
1x=3
1x-5=-2
3x-5
C
3(3)-5=4
The End
Homework
Worksheet Page 186: 4-9 ALL
Worksheet Page 187: 1-3 ALL