## Plane Geometry

Plane geometry is a two dimensional figure, also called planar geometry, with edges. The edges are line segments or sides and curve segments or arcs, all lying on a flat plane.

## plane Geometry Types

**Plane Geometry**(a shape like lines, circles and triangles)- Circle - A two-dimensional figure where all points are at a fixed equal distance from a center point. See [ 1 ]

- Circle Sector - A part of the interior of a circle having two radius boundries and an arc.
- Half circle - Half of the interior of a circle having a straight chord and an arc. See [ 1 ]
- Hollow circle - Two circles each having all points on each circle at a fixed equal distance from a center point. See [ 1 ]
- Quarter circle - A part of the interior of a circle having two radius boundries at a 90° angle and an arc. See [ 1 ]
- Thin wall circle - Two circles each having all points on each circle at a fixed equal distance from a center point. See [ 1 ]

- Ellipse - A two-dimensional figure with a conic section or a stretched circle.
- Polygon - A two-dimensional figure that is a closed plane figure for which all edges are line segments and not necessarly congruent.
- Concave polygon - A two-dimensional figure that is a polygon where one or more angles are greater than 180° and some vertices point inward.
- Convex polygon - A two-dimensional figure that is a polygon where all interior angles are less than 180° and all vertices point outward.
- Irregular polygon - A two-dimensional figure that is a polygon where all edge and angles are not the same. It can be concave or convex.
- Regular polygon - A two-dimensional figure that is a polygon where all edges are congruent and all angles are congruent.
- Self-intersecting polygon - A two-dimensional figure that is a polygon where one or more edges cross over another.

- Triangle - A two-dimensional figure that is a polygon with three edges.

- Right Isosceles Triangle - A two-dimensional figure that has one edge a right 90° interior angle and the other two angles are 45°.
- Right Triangle - A two-dimensional figure that has one side a right 90° interior angle.
- Equilateral Triangle - A two-dimensional figure that has three edges that are the same length and all sides and angles are congruent.
- Isosceles Triangle - A two-dimensional figure that has two edges that are the same length or at least two congruent sides.
- Oblique Triangle - A two-dimensional figure that is tilted at an angle, not horizontal or vertical.

- Acute Triangle - A two-dimensional figure that has all three angles less than 90°.
- Obtuse Triangle - A two-dimensional figure that has one of the three angles more than 90°.

- Scalene Triangle - A two-dimensional figure where all three edges are different lengths and all three angles are different angles.

- Quadrilateral - A two-dimensional figure that is a polygon with four edge.

- Kite - A two-dimensional figure that is a quadrilateral with two pairs of adjacent sides that are congruent.
- Parallelogram - A two-dimensional figure that is a quadrilateral with two pairs of parallel opposite sides.
- Rectangle - A two-dimensional figure that is a quadrilateral with two pair of parallel edges. See [ 1 ]

- Cross - Two rectangles that intersect perpendicular at a center point. See [ 1 ]
- Hollow rectangle - A two-dimensional figure that is a quadrilateral with two pair of parallel edges. See [ 1 ]
- Square angle - Two rectangles that intersect at a 90° angle at one end each. See [ 1 ]
- Square channel - Three rectangles that intersect at 90° angles at each end of one rectangle. See [ 1 ]
- Square I beam - Three rectangles, two that intersect at the center at 90° angles to the end of one rectangle. See [ 1 ]
- Thin wall rectangle - A two-dimensional figure that is a quadrilateral with two pair of parallel edges. See [ 1 ]
- Zed - Three rectangles, two that intersect at a 90° angle to the third one at end each at different directions. See [ 1 ]

- Rhombus - A two-dimensional figure that is a parallelogram with four congruent sides.
- Trapezoid - A two-dimensional figure that is a quadrilateral that has a pair of parallel opposite sides.

- Isosceles Trapezoid - A trapezoid with only one pair of parallel edges and having base angles that are the same.

- Square - A two-dimensional figure that is a quadrilateral with four equal side lengths and 90° interior angles. See [ 1 ]

- Pentagon - A two-dimensional figure that is a polygon with five sides.
- Regular Pentagon is a two-dimensional figure that is a polygon with five congruent sides.
- Hexagon - A two-dimensional figure that is a polygon with six sides.
- Regular Hexagon - A two-dimensional figure that is a polygon with six congruent sides.
- Heptagon - A two-dimensional figure that is a polygon with seven sides.
- Regular Heptagon - A two-dimensional figure that is a polygon with seven congruent sides.
- Octagon - A two-dimensional figure that is a polygon with eight sides.
- Nonagon - A two-dimensional figure that is a polygon with nine sides.
- Decagon - A two-dimensional figure that is a polygon with ten sides.
- Hendecagon - A two-dimensional figure that is a polygon with eleven sides.
- Dodecagon - A two-dimensional figure that is a polygon with twelve sides.
- Triskaidecagon - A two-dimensional figure that is a polygon with thirteen sides.
- Tetrakaidecagon - A two-dimensional figure that is a polygon with fourteen sides.
- Pentadecagon - A two-dimensional figure that is a polygon with fifteen sides.
- Hexakaidecagon - A two-dimensional figure that is a polygon with sixteen sides.
- Heptadecagon - A two-dimensional figure that is a polygon with seventeen sides.
- Octakaidecagon - A two-dimensional figure that is a polygon with eighteen sides.
- Enneadecagon - A two-dimensional figure that is a polygon with nineteen sides.
- Icosagon - A two-dimensional figure that is a polygon with twenty sides.

- Triangle - A two-dimensional figure that is a polygon with three edges.

[ 1 ] See Geometric Properties of Structural Shapes.

- Circle - A two-dimensional figure where all points are at a fixed equal distance from a center point. See [ 1 ]