TrianglesTrianglesI can differentiate between the I can differentiate between the

different types of triangles.different types of triangles.

Created by: Maggie Howe and Rachel Tankersley

Sycamore Elementary 5th grade

Essential Questions: Essential Questions:

What is a triangle?

How do you classify triangles?

What is an acute triangle?What is a right triangle?What is an obtuse triangle?

What is an isoscelse triangle?What is an equilateral triangle?What is a scalene triangle?

Triangles are everywhere.Triangles are everywhere. They can be found bracing a bridge.They can be found bracing a bridge.

Triangles can be found racking up billiard Triangles can be found racking up billiard balls.balls.

Triangles can be classified by sides.

OR

Triangles can be classified by angles.

TRIANGLES BY SIDESTRIANGLES BY SIDES

SCALENESCALENE

ISOSCELESISOSCELES

EQUILATERALEQUILATERAL

SCALENE TRIANGLESCALENE TRIANGLE

WHEN 3 PEOPLE WHEN 3 PEOPLE GET ON THE GET ON THE SCALES TO SEE SCALES TO SEE HOW MUCH THEY HOW MUCH THEY WEIGHT, EACH ONE WEIGHT, EACH ONE WEIGHS A WEIGHS A DIFFERENT DIFFERENT AMOUNT. AMOUNT. SO…………SO…………

A scalene triangle has A scalene triangle has no equal sides.no equal sides.

All sides are different All sides are different lengths. lengths.

Isosceles TrianglesIsosceles Triangles Isosceles triangles Isosceles triangles

have 2 equal sides.have 2 equal sides. The angles The angles

opposite the equal opposite the equal sides are also sides are also equal. <B = <C AB equal. <B = <C AB = AC= AC

Equilateral TrianglesEquilateral Triangles

All 3 sides of an All 3 sides of an equilateral triangle are equilateral triangle are equal.equal.

Each angle of an Each angle of an equilateral triangle are equilateral triangle are equal.equal.

Each angle must be Each angle must be 60 degrees.60 degrees.

Now let’s review.Now let’s review.

What kind of triangle has all 3 sides and What kind of triangle has all 3 sides and angles equal?angles equal?

Equilateral TriangleEquilateral Triangle

What kind of triangle has all sides a different What kind of triangle has all sides a different length ?length ?

SCALENE TRIANGLESCALENE TRIANGLE

What kind of triangle has 2 equal sides?What kind of triangle has 2 equal sides?

AN ISOSCELES TRIANGLEAN ISOSCELES TRIANGLE

TRIANGLES BY ANGLESTRIANGLES BY ANGLES

AcuteAcute

RightRight

ObtuseObtuse

A right triangle has one 90 degree or A right triangle has one 90 degree or RIGHT angle.RIGHT angle.

Acute trianglesAcute triangles3 angles less than 90 degrees.3 angles less than 90 degrees.

OBTUSE TRIANGLEOBTUSE TRIANGLE

An obtuse triangle has one obtuse angle. An obtuse triangle has one obtuse angle.

What type of triangle is this?What type of triangle is this?

Use right, obtuse, or acute.Use right, obtuse, or acute.

What type of triangle is this?What type of triangle is this?

Use right, obtuse, or acute.Use right, obtuse, or acute.

What type of triangle is this?What type of triangle is this?

Use right, obtuse, or acute.Use right, obtuse, or acute.

What type of triangle is this?What type of triangle is this?

Use right, obtuse, or acute.Use right, obtuse, or acute.

What type of triangle is this?What type of triangle is this?

Use right, obtuse, or acute.Use right, obtuse, or acute.

What type of triangle is this?What type of triangle is this?

Use isosceles, scalene, or equilateral.Use isosceles, scalene, or equilateral.

What type of triangle is this?What type of triangle is this?

Use isosceles, scalene, or equalateral.Use isosceles, scalene, or equalateral.

What type of triangle is this?What type of triangle is this?

Use isosceles, scalene, or eqilateral.Use isosceles, scalene, or eqilateral.

What type of triangle is this?What type of triangle is this?

Use isosceles, scalene, or equilateral.Use isosceles, scalene, or equilateral.

What type of triangle is this?What type of triangle is this?

Use isosceles, scalene, or equilateral.Use isosceles, scalene, or equilateral.

Which one of these is labeled Which one of these is labeled incorrectly?incorrectly?

Right Triangle Equilateral Triangle Scalene Triangle

3322

Follow UpFollow UpDraw an acute triangle.Draw a right triangle.Draw an obtuse triangle.

Draw an isoscelse triangle.Draw an equilateral triangle.Draw a scalene triangle.

Answer the following questions:

Can you have an acute, scalene triangle?Can you have a right isoscelese triangle?Can you have an obtuse, equilateral triangle?