# Triangles

Free Math Games & Activities for Kids

A **triangle** is a polygon with three edges and three
vertices. There are three sides and three angles in every triangle.
The three angles always add up to 180°. There are special names
given to triangles that tell you how many sides or angles are equal.
An equilateral triangle has 3 equal sides, the 3 Angles are
60° each. An isosceles triangle has 2 equal sides. A scalene
triangle has no equal sides.

**perimeter**of the triangle is the distance around the edge. To find the perimeter just add up the 3 sides.

The

**area**of a triangle is half of the base times the height. 1/2 b x h = area

An

**angle**consists of two rays with a common endpoint. The two rays is called the side of the angle and the common endpoint is the vertex of the angle. Each angle has a measurement generated by the rotation about the vertex. The measure is determined by the rotation of the terminal side about the initial side. Angles can be classified based upon the measure.

Types of angles are usually based on angle measurement

An Acute Angle is an angle which measures less than 90°.

A Right Angle measures exactly 90°

An Obtuse Angle measures greater than 90° but less than 180°

A Straight Angle measures exactly 180°

A Reflex Angle measure is greater than 180° but less than 360°

**Trigonometry** is a branch of mathematics. Trigonometry studies
the relationships between side lengths and angles of triangles. There are six
ratios including sine, cosine, tangent, cosecant, secant and cotangent.
These six trigonometry ratios are abbreviated as sin, cos, tan, csc, sec, and
cot. These are referred to as ratios since they can be expressed in terms of the
sides of a right angled triangle for a specific angle.

**
Trigonometric functions**

Trigonometric functions are functions related to an angle. There are six
trigonometric functions: sine, cosine, tangent and their reciprocals cosecant,
secant, and cotangent, respectively. Sine, cosine, and tangent are the most
widely used trigonometric functions. Their reciprocals, though used, are less
common in modern mathematics. Trigonometric functions are also called circular
functions.

There are two main ways in which trigonometric functions are typically
discussed: in terms of right triangles and in terms of the unit
circle. The right-angled triangle definition of trigonometric
functions is most often how they are introduced, followed by their definitions
in terms of the unit circle.

Types of Triangles based on Sides

Types of Triangles based on Angles

Free Presentations in PowerPoint format

Classroom Lesson Plan common core math ANGLES

Common core math grade 3-5 lesson plan for measuring angles

Perimeter and Area

Geometry games (Shodor Interactive)

Shape Games

Planarity

Angles

Coordinates

Triangles

Squares

Polygons

Free Presentations in PowerPoint format

Trigonometry Explained step-by-step in PDF form

Simplified version how to learn trigonometry

Free downloadable college trigonometry math book

YouTube video explaining trigonometry math ideas