Definition – Triangle can be defined as a closed shaped two dimensional, plane figure with 3 vertices and 3 straight sides.
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Triangle can also be defines as – a closed polygon with 3 sides and 3 vertices.
Definition of Polygon : A closed shaped, 2 dimensional, plane figure with minimum of 3 vertices, and 3 sides and maximum of n vertices and n sides.
Types of triangle –
B. On the basis of angles ;
1. Acute angled triangle – all interior angles are less than 90 degree.
2. Obtuse angled triangle – any one of interior angle is more than 90 degree.
3. Right angled triangle – Any one of the interior angle equals 90 degree.
Properties of a triangle ;
1. Triangle has 3 sides and 3 angles.
2. Sum of all the angles of a triangle is always 180 degree.
3. Exterior angles of triangle always adds upto 360 degree.
4. Sum of consecutive interior and exterior angles is supplementary.
5. Sum of lengths of any 2 sides of triangle is always greater than the third side, following which the difference between any 2 sides is always less than the third side.
6. Shortest side always lies opposite the smallest angle and longest side always lies opposite the largest angle.
