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Plane Figures: Plane figures are closed, two dimensional figures. These are shapes that we can easily draw, such as a triangle or a square. When we study plane figures, we will be looking at the following: 1. Triangles 2. Quadrilaterals 3. Pentagons 4. Hexagons 5. Heptagons 6. Octagons Terms to Know: Edge: the side of a plane figure. Vertex: the corner of a plane figure, where two edges meet. Vertices: more than one vertex. Angle: the area inside a vertex on a plane figure. 1. Acute – angle is less than 90°. 2. Right – angle is exactly 90°. Looks like the vertex on a piece of uncut paper. 3. Obtuse – angle is greater than 90°. Congruent: same size and shape. Equal. Parallel: opposite lines, or edges, going in the same direction. The edges, or lines, will never cross. Triangles: three edged, three vertices, and three angled plane figures. There are three main types of triangles. 1. Equilateral – All edges are congruent. All angles are congruent. 2. Isosceles – Two edges are congruent. Two angles are congruent. 3. Scalene – No edges are congruent. No angles are congruent. Quadrilaterals: four edged, four vertices, four angled plane figures. There are many different types of quadrilaterals. 1. Square - a four edge, four vertices, and four angle plane figure. All the edges are congruent. All of the angles are exactly 90°. 2. Rectangle - a four edge, four vertices, and four angle plane figure. Parallel sides are congruent. All of the angles are exactly 90°. 3. Parallelogram - a four edge, four vertices, and four angle plane figure. Parallel sides are congruent. Opposite angles are congruent. Not all of the angles have to be 90°. 4. Trapezoid - a four edge, four vertices, and four angle plane figure. It has one set of parallel edges. The other edges would cross if they were to be extended. 5. Rhombus - a four edge, four vertices, and four angle plane figure. All of the sides are congruent. Opposite angles are congruent. Not all of the angles have to be 90° Pentagons: five edged, five vertices, five angled plane figures. Hexagon: six edged, six vertices, six angled plane figures. Heptagons: seven edged, seven vertices, seven angled plane figures. Octagon: eight edged, eight vertices, eight angled plane figures. Explore the links to learn about the different plane figures mentioned here. |
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