Polygons and Circles (Project in Mathematics)

*Polygons And Circles

this presentation is written G

As your can see here……There are triangles, squares,rectangles,circles,and other plane figures. These plane figures are called polygons.A polygons is a closed plane figure bounded by line segments. A circle is an exception. It is not a polygon since it is not bounded by line segments.

Here are some examples of polygons.

on the other hand, the following figures are not polygons

Number of sides Name Figure

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon

Number of sides Name Figure8 Octagon

9 Nonagon

10 Decagon

11 Undecagon

12 Dodecagon

* Triangles and quadrilaterals are further classified into different kinds.Triangles are polygons with three sides, three angles,

and three vertices. The sum of the interior angles of a triangle is 180°. Triangles are classified in two ways…

*According to the Lengths of the

Sides

Triangle Characteristics FigureEquilateralTriangle (also called an equiangular Triangle)

• All sides are congruent or have equal lengths.

• Each angle measures 60° Therefore, all angles are congruent or have equal measures.

Isosceles triangle

• Two sides are congruent.

• Angles opposite congruent sides are congruent.

Scalene triangle• No sides are

congruent.• No angles are

congruent.

*According to the Angle Measures

Triangle Characteristics

Figure

Acute triangle All angles are acute.

Right triangle One angle is a right angle.

Obtuse triangle One angle is obtuse.

* are polygons with four sides, four angles, and four vertices. The sum of the interior angles of a quadrilateral is 360°

* Quadrilaterals

*The kinds of Quadrilaterals

Quadrilateral characteristics FigureRectangle • Two pairs of opposite

sides are congruent.• It contains four right

angles.

Square • Four sides are congruent.• It contains four right

angles.

Parallelogram • Tow pairs of opposite sides are congruent and parallel.

• Opposite angles are congruent.

Rhombus • Four sides are congruent.• Two pairs of opposite

sides are parallel.• Opposite angles are

congruent.

Trapezoid one pair of opposite sides is parallel.

A circle is a set of all points in a plane equidistant from a fixed point. The fixed point is called the center and the fixed distance from the center to a point on the circle Is the radius. A circle is named after its center. Recall that a circle is not a polygon because it is not bounded by line segments.Here is the example…..

A

O

C

D

F I1

In the figure on the previous page, the parts of a circle are illustrated.

1. center-point O2. Radius(plural:radii)-, A radius of a circle is a line segment from any point on the circle to its center. A radius of a circle measures half its diameter.3. chord- 4. diameter- A chore passing through the center of a circle is called a diameter. A diameter of a circle measures twice its radius.5. secant-I1 A secant is a line that intersects a circle at exactly two points.

6. Tangent-I2

Oh wait where is the circle…..There ok lets continuepoint of tangency-point A A tangent is a line that intersects a circle at exactly one point. This point is called the point of tangency.

By: Marigold So

Thaaaanks…

THE END