Exploring Triangle Sum and Exterior Angle Theorem

The video tutorial covers the definition and classification of triangles by their sides and angles. It explains the exterior angle theorem and provides examples of solving triangle problems using this theorem. The tutorial emphasizes the importance of understanding that the sum of all angles in a triangle is 180 degrees.

What is the definition of a triangle?

• A polygon with five sides

• A shape with no sides

• A polygon with three sides

• A polygon with four sides

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CCSS.HSG.CO.A.1

How many congruent sides does an equilateral triangle have?

• One

• All three

• At least two

• None

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According to the exterior angle theorem, the measure of an exterior angle of a triangle is equal to:

• The difference of the nonadjacent interior angles

• The sum of the nonadjacent interior angles

• The product of the adjacent interior angles

• The sum of the adjacent interior angles

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CCSS.7.G.B.5

If a triangle has two congruent sides, it is classified as:

• Right

• Isosceles

• Equilateral

• Scalene

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CCSS.HSG.CO.B.8

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A triangle with sides of lengths 5, 7, and 10 is classified as:

• Right

• Scalene

• Isosceles

• Equilateral

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What type of triangle has one angle that is exactly 90 degrees?

• Right

• Obtuse

• Equilateral

• Acute

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A triangle with all angles less than 90 degrees is called:

• Right

• Acute

• Obtuse

• Scalene

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What is the sum of all angles in a triangle?

• 90 degrees

• 180 degrees

• 270 degrees

• 360 degrees

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CCSS.HSG.CO.C.10

If one angle of a triangle is 90 degrees and another is 35 degrees, what is the measure of the third angle?

• 75 degrees

• 45 degrees

• 55 degrees

• 65 degrees

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CCSS.HSG.CO.C.10

Using the exterior angle theorem, if one exterior angle is 158 degrees and one of the nonadjacent interior angles is 70 degrees, what is the measure of the other nonadjacent interior angle?

• 88 degrees

• 68 degrees

• 90 degrees

• 70 degrees

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CCSS.HSG.CO.C.10