Answer:

1. Parallel lines are two or more lines that never intersect, no matter how far they are extended. There are no other terms that need to be defined first.

2. Perpendicular lines are two lines that intersect at a 90-degree angle. In order to define perpendicular lines, you would need to first define what it means for lines to intersect.

3. A line segment is a part of a line that is bounded by two endpoints. In order to define a line segment, you would first need to define what a line is.

4. The radius of a circle is the distance from the center of the circle to any point on the edge of the circle. In order to define the radius of a circle, you would first need to define what a circle is.

5. A square is a four-sided polygon with four equal sides and four right angles. In order to define a square, you would first need to define what a polygon is and what it means for a polygon to have sides and angles.

Verified answer

Answer:

Parallel line - Two lines are said to be parallel when (a) They never meet or never intersect each other even if they are extended to the infinity. (b) they coplanar.

(ii) Perpendicular lines - Two lines AB and CD lying the same plane are said to be perpendicular, if they form a right angle. We write AB⊥CD

(iii) Line segment - A line-segment is a part of line. When two distinct points, say A and B on a line are given, then the part of this line with end-points A and B is called the line-segment.

(iv) Radius of a circle - The distance from the centre to a point on the circle is called the radius of the circle. In the following figure OP is the radius.

(v) Square - A quadrilateral in which all the four angles are right angles and four sides are equal is called a square. ABCD is a square.

Step-by-step explanation:

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