Section 12.3

A polygon is a simple closed plane figure made up of line segments.

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12.3 -Polygons PG 500

Every interior angle of a convex polygon has a measure less than 180°. WE WILL ONLY BE FOCUSING ON CONVEX POLYGONS!

​​Convex Polygons

A concave polygon has at least one interior angle with a measure greater than 180°.

​​Concave Polygons

Multiple Choice

Which type of polygon is this?

• Convex

• Concave

Multiple Choice

What type of polygon is this?

• Convex

• Concave

Multiple Choice

What type of polygon is this?

• Concave

• Convex

Draw

Draw a convex polygon

Each segment making up the polygon is a side. Any two adjacent sides of a polygon meet in a vertex. Polygons are named according to the number of their sides. In a regular polygon, all sides have the same length and all angles have the same measure.

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Polygons

Multiple Choice

Which is a regular polygon?

The polygon with the fewest possible number of sides is the triangle.

Triangles are classified by the lengths of their sides.

​Triangles are also classified by the measures of their angles.

​Triangles PG 501

Multiple Choice

What type of triangle is this?

• acute equilateral

• obtuse scalene

• right isosceles

Multiple Choice

What type of triangle is this?

• acute equilateral

• obtuse scalene

• right isosceles

Multiple Choice

What type of triangle is this?

• acute equilateral

• obtuse scalene

• right isosceles

Triangle Theorem

Applying the Triangle Theorem

Multiple Choice

Identify this type of triangle according to the length of their sides.

• isosceles

• scalene

• equilateral

Multiple Choice

Identify this type of triangle according to the lengths of their sides

• isosceles

• scalene

• equilateral

Multiple Choice

Write and and solve the equation to find $$m\angle\ x$$

• $$m\angle\ X\ =\ 150\degree$$

• $$m\angle\ X\ =\ 90\degree$$

• $$m\angle\ X\ =\ 40\degree$$

Multiple Choice

Classify the following triangles according to the measures of their angles.

• right

• acute

• obtuse

Multiple Choice

Classify the following triangles according to the measures of their angles.

• right

• acute

• obtuse