A triangle is a polygon
It has three edges and three vertices
An equilateral triangle is a triangle measuring 60°
An isosceles triangle has two sides of equal length.
Area of a circle
The circumference of a circle is the distance around it
Circumference is used by some authors to denote the perimeter of an ellipse.
The area of a shape can be measured by comparing the shape to squares of a fixed size.
written as m2
For a solid shape such as a sphere, cone, or cylinder, the area of its boundary surface is called the surface area.