A line has length between two points but no width.
A point has no components i.e. it can’t be divided into parts.
A straight line traces the closest distance between two points.
A curved line has no straight segments.
A surface or a plane is a completeky flat surface between its border lines. Lines constitutes the borders of planes.
Two straight lines are said to intersect each other in a point where they meet. The inclination between those lines is called the angle between the lines.
The point of intersection is called the vertex of the angle.
A circle is a planar figure limited by a curved line called the perimeter or periphery.
The distance from the center to the perimeter is called the radius and is everywhere on the circle the same.
The diameter is a straight line from periphery to peiriphery through the center of the circle. It divides the circle into two equal parts-half-circles.
A triangle is a figure made up of three straight lines. These are called its sides.
A quadrilateral figure is made up of four straight lines.
A polygonal figure is borders by more than four straight lines.
A triangle composed of three equal sides is called equilateral.
A triangle having two equal sides is termed isosceles triangle.
A right triangle has a perpendicular angle.