Two-Dimensional Figures Geometry Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Warm Up Classify the angle as acute; right angle, obtuse or straight. 2) 2) 1) 1) Acute Right angle 3) 3) Obtuse 4) 4) Straight Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Polygon Flat figures such as squares, rectangles are two-dimensional figures. A polygon is a simple, closed, two-dimensional figure formed by three or more sides. The number of sides determine a polygon’s name. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Polygon Triangle (3 sides) Pentagon (5 sides) Quadrilateral (4 sides) Octagon (8 sides) Hexagon (6 sides) Heptagon (7 sides) Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Polygon Tri: three Quad: four Penta: five Hexa: six Hepta: seven Octa: eight Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Polygon Lateral: comes from the Latin word meaning side -gon: comes from the Greek word for angle Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Regular Polygon When all sides of a polygon are congruent and all of the angles are congruent, the polygon is a regular polygon The polygon has 5 sides. So, it is a pentagon. Since the sides and angles are congruent, it is a regular polygon. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Your Turn! Identify the polygon. Then tell if it is a regular polygon. The polygon has 7 sides. So, it is a heptagon. Since the sides and angles are not congruent, it is not a regular polygon. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Triangles Step 1: Draw a triangle similar to the one shown below. Then tear off each corner. Step 2: Rearrange the torn pieces as shown. 1 1 2 3 2 3 When you arrange the angles, a line is formed. By extending the line, you find 180° on the protractor. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Triangles Step 3: Repeat Steps 1 and 2 with a different triangle. Therefore, the sum of the measures of the angles of a triangle. Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Triangles Triangles can be classified according to their angles. Acute Right Obtuse All angles are acute One angle is right angle One angle is obtuse Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Your Turn! Find the missing angle measure for each triangle. Then classify each triangle as acute, right, or obtuse. 30° x° 45° 60° 63° x° 95° x° 20° 40° Obtuse 57° Acute 130° Obtuse Copyright © Ed2Net Learning, Inc.

Special names of triangles Figure Characteristic Scalene Triangle No sides congruent Isosceles triangle At least two sides are congruent Copyright © Ed2Net Learning, Inc.

Special names of triangles Figure Characteristic Equilateral triangle All sides are congruent All angles are congruent Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Quadrilaterals Quadrilaterals can be classified by their sides and angles. Copyright © Ed2Net Learning, Inc.

Special names of quadrilaterals Figure Characteristic Rectangle Opposite sides congruent All angles are at right angles Opposite sides are parallel Square All sides are congruent All angles are right angles Opposite sides are parallel Copyright © Ed2Net Learning, Inc.

Special names of quadrilaterals Figure Characteristic Parallelogram Opposite sides congruent Opposite sides parallel Opposite angles congruent Rhombus All sides congruent Opposite sides parallel Opposite angles congruent Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Your Turn! How are rectangles and squares alike? How do they differ? Sample answer: similarities- four sides, closed figures, opposite sides equal, opposite sides parallel; differences-squares have four congruent sides Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Assessment Draw an example of each polygon listed. Mark any congruent sides, congruent angles, and right angles. Hexagon Regular octagon Parallelogram Triangle Equilateral Triangle Rectangle Check student’s responses Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Assessment Tell whether each statement is sometimes, always, or never true. Parallelograms are squares sometimes A rhombus is a square sometimes A rectangle is a parallelogram always A square is a rhombus always Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Review A polygon is a simple, closed, two-dimensional figure with three or more sides. When all the sides and angles of a polygon are congruent, then the polygon is congruent. Scalene, Isosceles and Equilateral are three types of triangles Rectangle, square, parallelogram, and rhombus are types of quadrilaterals Copyright © Ed2Net Learning, Inc.

Copyright © Ed2Net Learning, Inc. Thank You! Remember to do the practice worksheets!!! Copyright © Ed2Net Learning, Inc.