9.) a. Parallel lines do not intersect  b. If line m and line n are parallel lines and then they________

a. intersect

b. do not intersect

c. are parallel

10.) a. A triangle is a polygon with 3 sides.  b. If it is a triangle then_____

a. it is a polygon

b. it is a triangle

c. it has three sides

Examples. Given the conditional statement "If a polygon has 3 sides, then it is a triangle", the contrapositive is "If a polygon is not a triangle, then it does not have 3 sides".

the line is parallel if and only if extending line in the same direction and remaining the same distance apart, It also parallel if the lines that are in the same plane that do not intersect.