The World Of TrianglesFree powerpoints at http://www.worldofteaching.com

TrianglesA triangle is a 3-sided polygon. Every triangle has three sides and three angles. When added together, the three angles equal 180.

Acute TrianglesA triangle in which all three angles are less than 90.

Obtuse TrianglesAn obtuse triangle is a triangle in which one of the angles is greater than 90.

Right TrianglesA right triangle is triangle with an angle of 90.

Scalene TrianglesA triangle with three unequal sides.

Isosceles TrianglesAn isosceles triangle is a triangle with (at least) two equal sides.

Isosceles Triangle Theorem The following movie shows that if two sides of a triangle are congruent, then the angles opposite those sides are congruent.

Equilateral TrianglesAn equilateral triangle is a triangle with all three sides of equal length.

Equiangular TrianglesAn equiangular triangle is a triangle which has three equal angles.

Congruent TrianglesCongruent triangles are triangles whose corresponding angles and sides are congruent. They are exactly the same size and shape.

The HypotenuseThe hypotenuse of a right triangle is the triangle's longest side, i.e., the side opposite the right angle.

The Pythagorean TheoremFor a right triangle with legs a and b and hypotenuse c, a2+b2=c2.

Triangle QuizPlease complete the following quiz that covers the information that was just presented to you.

Question 1If a triangle has three unequal sides it is a ______ triangle.A) ScaleneB) ObtuseC) IsoscelesAnswer:A) Scalene

Question 2A triangle which has three equal angles is a ______ triangle.A) AcuteB) EquilateralC) EquiangularAnswer:C) Equiangular

Question 3A triangle with (at least) two equal sides is a ______ triangle.A) ScaleneB) IsoscelesC) CongruentAnswer:B) Isosceles

Question 4Two triangles that are equal are called ______ trianglesA) Acute B) Obtuse C) Congruent Answer:C) Congruent

Question 5A triangle with all three sides of equal length is a ______ triangle.A) EquilateralB) RightC) EquiangularAnswer:A) Equilateral

Question 6A triangle with an angle of 90 is a ______ triangle.A) AcuteB) RightC) CongruentAnswer:B) Right

Question 7A triangle in which all three angles are less than 90 is a ______ triangle.A) RightB) AcuteC) ScaleneAnswer:B) Acute

Question 8A triangle in which one of the angles is greater than 90 is a ______ triangle.A) ObtuseB) IsoscelesC) AcuteAnswer:A) Obtuse

Question 9What is the Hypotenuse of a right triangle?A) The smallest angle.B) The side opposite the right angle.C) The right angle.Answer:B) The side opposite the right angle.

Question 10The Pythagorean Theorem states A) pr2B) (a+b)2/2=cC) a2+b2=c2

Answer:C) a2+b2=c2

Question 11Use the Pythagorean Theorem to solve the following:a = 5b = 12c = ?Answer:c = 13