GETTING TO KNOW TRIANGLES

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GETTING TO KNOW TRIANGLES

• 7TH GRADE MATH
• BY MRS. BRUSH

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

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• Triangles can be found racking up billiard balls.

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Triangles can be seen holding up shelves.
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• A triangle is a polygon with 3 sides.
• Triangles can be classified by sides.
• Triangles can be classified by angles.

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TRIANGLES BY SIDES

• SCALENE
• ISOSCELES
• EQUILATERAL

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SCALENE TRIANGLE

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

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• A scalene triangle has no equal sides.
• All sides are different lengths.

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Isosceles Triangles

• Isosceles triangles have 2 equal sides.
• The angles opposite the equal sides are also
  equal. ltB ltC AB AC

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Equilateral Triangles

• All 3 sides of an equilateral triangle are equal.
• Each angle of an equilateral triangle are equal.
• Each angle must be 60 degrees.

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• Now lets review.
• What kind of triangle has all 3 sides and angles
  equal?

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Equilateral Triangle
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• What kind of triangle has all sides a different
  length ?

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SCALENE TRIANGLE
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• What kind of triangle has 2 equal sides?

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AN ISOSCELES TRIANGLE
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TRIANGLES BY ANGLES

• Acute
• Right
• Obtuse

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Acute trianglesAll angles are less than 90
degrees.
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• A right triangle has one 90 degree angle.

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OBTUSE TRIANGLE

• An obtuse triangle has one obtuse angle. The
  obtuse angle is more than 90 but less than 180
  degrees.

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DISCUSSION QUESTIONS

• Is it possible to have a right equilateral
  triangle?
• Could you have a triangle that is isosceles and
  acute?

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CREDITS

• Microsoft clip art.
• wwwmath.com/school/subject/practice
• www.harcourtschool.com/glossary/math2