Define and Sketch Triangles

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NEO Tue, Jan 25, 2022 07:57 AM UTC

This pdf covers, the types of triangles and their properties. A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.

1. What is a Triangle?
In geometry, a triangle is a closed, two-dimensional shape with three straight sides. A triangle is
also a polygon.
We can find the shape of a triangle in a flag, the musical instrument triangle, and a roadside
Properties of a Triangle

2. ● A triangle has three sides, three vertices, and three angles.
● The sum of the three interior angles of a triangle is always 180°.
● The sum of the length of two sides of a triangle is always greater than the length of the
third side.
● A triangle with vertices P, Q, and R is denoted as △PQR.
● The area of a triangle is equal to half of the product of its base and height.
Different Types of Triangles
To classify triangles according to their angles, we measure each of its interior angles. Triangles
can be classified by angles, as:
● Acute Triangle ● Right Triangle ● Obtuse Triangle
An acute triangle has all interior angles acute (less than 90°), a right triangle has one right angle
(equal to 90°) and an obtuse triangle has one obtuse angle (greater than 90°).

3. To classify the triangles according to their sides, we measure the length of each of its sides.
Triangles can be classified by their sides, as:
● Equilateral Triangle ● Isosceles Triangle ● Scalene Triangle
To classify triangles according to both angles and sides, we measure the interior angles and
length of the sides of the triangle. Few examples of triangles classified on the basis of both
angles and sides are:
● Acute Equilateral ● Right Isosceles ● Obtuse Scalene
Triangle Triangle Triangle
Fun Facts
● A triangle can always be split into two right triangles, irrespective of its orientation.
● Triangles are polygons with the least number of sides.

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