Area and Perimeter of Plane Figure
- Perimeter is the length of the boundary of a closed figure.
- The perimeter of a polygon is the sum of the lengths of all its sides.
In case of a triangle ABC, with sides of lengths a, b and c units:
Perimeter of ABC = AB + BC + AC = a + b + c
- The semi-perimeter of a triangle is half the perimeter of the triangle.
The semi-perimeter (s) of a triangle with sides a, b and c is.
- The semi-perimeter of a triangle is used for calculating its area when the length of altitude is not known.
- Area of a triangle:
- Area of a triangle =
- All the congruent triangles are equal in area, but the triangles having equal areas may or may not be congruent.
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