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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. - PowerPoint PPT Presentation
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CLASSIFYING TRIANGLES BY ANGLES
Classifying Triangles by Angles• ACUTE
• OBTUSE
• RIGHT
• EQUIANGULAR
ACUTE TRIANGLE
•All interior angles are acute (or have a measure less than 90°)
Interior Angle
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
•All interior angles are congruent (exactly the same measure)
Interior Angle
•All interior angles ALWAYS measure 60° for an equiangular triangle
Examples of Equiangular Triangles
OBTUSE TRIANGLE
•ONE interior angle is obtuse (or has a measure greater than 90°)
Obtuse Angle
•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
•ONE interior angle is a right angle (or has a measure equal to 90°)
Right Angle
•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
• OBTUSE
• RIGHT
• EQUIANGULAR
YOU TRY
• ACUTE
• OBTUSE
• RIGHT
• EQUIANGULAR
YOU TRY
• ACUTE
• OBTUSE
• RIGHT
• EQUIANGULAR
YOU TRY
• ACUTE
• OBTUSE
• RIGHT
• EQUIANGULAR
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
•Two sides are congruent (exactly the same length)•The angle between the congruent sides is called
the VERTEX ANGLE
VERTEX
Examples of Isosceles Triangles
SCALENE TRIANGLE
•NO sides are congruent
Examples of Scalene Triangles
Classifying Triangles
ACUTE ISOSCELES
Angles are classified first by ANGLE
And then by SIDE
ACUTEISOSCELES
Classifying Triangles
RIGHT SCALENE
Angles are classified first by ANGLE
And then by SIDE
RIGHTSCALENE
Classifying Triangles
OBTUSE SCALENE
Angles are classified first by ANGLE
And then by SIDE
OBTUSE SCALENE
YOU TRY
• RIGHT ISOSCELES
• ACUTE ISOSCELES
• EQUIANGULAR EQUILATERAL
• RIGHT SCALENE
YOU TRY
• ACUTE ISOSCELES
• OBTUSE SCALENE
• RIGHT EQUILATERAL
• EQUIANGULAR SCALENE
YOU TRY
• ACUTE ISOSCELES
• OBTUSE SCALENE
• EQUIANGULAR EQUILATERAL
YOU TRY
• ACUTE SCALENE
• OBTUSE SCALENE
• OBTUSE ISOSCELES
YOU TRYGiven: 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 C
Step 1Realize that an equiangular triangle is ALWAYS an equilateral triangle an therefore ALL sides are CONGRUENT.
Step 2AB=BC3x-5=2x-2
Step 3Combine ‘x’ term3x-5=2x-23x-5-2x=2x-2x-21x-5=-2
Step 4Solve for x1x-5+5=-2+51x=3
Step 5Plug x into original equation to find length3x-53(3)-5=4
The End
Homework
Worksheet Page 186: 4-9 ALLWorksheet Page 187: 1-3 ALL
YOU ARE CORRECT!
OH DOOFENSHMIRTZ!TRY AGAIN!