Warm Up 6.1 on desk Do daily Quiz 5.7

Section 6.1 Identify and classify polygons. Calculate angle measures of quadrilaterals. EQ: How do you classify Polygons and calculate their angle measures?

A polygon is a plane figure that is formed by three or more segments called sides.

A polygon is a plane figure that is formed by three or more segments called sides. No curves No gaps No criss-cross

The endpoint of each side is a vertex.

Is the figure a polygon? Explain your reasoning. Example 1 Identify Polygons Is the figure a polygon? Explain your reasoning. a. b. c. d. SOLUTION a. Yes. b. No. c. No. Yes. d. 6

The figure is a polygon with four sides, and it is a quadrilateral. Example 2 Classify Polygons Decide whether the figure is a polygon. If so, tell what type. If not, explain why. a. b. c. d. SOLUTION a. The figure is a polygon with four sides, and it is a quadrilateral. b. The figure is not a polygon c. The figure is a polygon with five sides, and it is a pentagon. The figure is not a polygon d. 7

Polygons are classified by the number of sides they have.

Triangle has three sides. Quadrilateral has four sides. Pentagon has five sides. Hexagon has six sides. Heptagon has seven sides. Octagon has eight sides.

Checkpoint Identify and Classify Polygons Decide whether the figure is a polygon. If so, tell what type. If not, explain why. 1. ANSWER No;. 2. ANSWER yes; pentagon 3. ANSWER yes; quadrilateral 4. ANSWER No;

Diagonal: A segment that joins two nonconsecutive vertices of a polygon

Theorem 6.1 Quadrilateral Interior Angles Theorem The sum of the measures of the interior angles of a quadrilateral is 360.

Theorem 6.1 Quadrilateral Interior Angles Theorem The sum of the measures of the interior angles of a quadrilateral is 360.

Example 3 Find the measure of S. SOLUTION Find Angle Measures of Quadrilaterals Find the measure of S. SOLUTION mP + mQ + mR + mS = 360° 70° + 80° + 70° + mS = 360° 220° + mS = 360° mS = 140° ANSWER The measure of S is 140°. 17

Checkpoint Find the measure of A. ANSWER 90° ANSWER 65° ANSWER 72° Find Angle Measures of Quadrilaterals Find the measure of A. ANSWER 90° ANSWER 65° ANSWER 72°

3. Determine whether the grid shows a reflection in the x-axis, the y-axis, or neither. the y-axis ANSWER 4. Find the number of lines of symmetry. 6 ANSWER

Determine whether figure B is a reflection of figure A. 1. No; the orientation is not reversed. ANSWER 2. Yes; all three properties of a reflection are met. ANSWER

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