(i) Parallel Lines :
If end points of two straight lines do not meet even if they are produced on both sides, they are called parallel lines.
Before definition concept of point, straight line is necessary.
Point : A point is that which has no part.
Straight line : A stgraight line is a line which lies evenly with the points on itself.
(ii) Perpendicular Lines :
If Angle between Vectors OA and OB is 90°, then only lines are perpendicular mutually.
Before definition concept of Ray and Angle is necessary.
Ray : Joining one end point and non-end point is called Ray.
Ray OA and Ray OB revolve and forms an angle.
(iii) Segment:
Segment is formed when two end points are joined. Here we must know point and straight line.
Point: It has only dimension, no length, breadth and thickness.
A – Starting point B – End point AB – Segment
Straight line : When two end points of a segment is produced on both sides, we get a straight line.
(iv) Radius of a Circle :
Circle is a set of points moves from a fixed point.
That equal distance is radius of the circle.
‘O’ – Fixed point
OA – radius of the circle.
Necessary terms — Point, Segment.
v) Square :
Square is a figure in which all sides and angles are equal.
AB = BC = CD = DA = 4 cms.
∠A = ∠B = ∠C = ∠D = 90°.
Necessary terms — Quadrilateral, angle.
Quadrilateral In a plane, if 3 points in 4 points are non-collinear and meet in different points, such figure is called quadrilateral.
Angle: ‘O’ is common point between vector OA and Vector OB Such figure is called an angle.
