- AParallel
- BIntersecting on the left
- CIntersecting on the right
- DThe same line
Step-by-Step Solution
90 + 90 = 180 degrees = two right angles, so the lines do not meet on either side; they are parallel.
Answer: A) Parallel
If two interior co-interior angles on the same side of a transversal are 90 degrees each, the two lines are ____.
Class 9Introduction to Euclid's GeometryGeometry — Foundations
Key idea: The five postulates of Euclid
**Postulate 1**: A straight line may be drawn from any one point to any other point.
**Postulate 2**: A terminated line (segment) can be produced indefinitely (extended).
**Postulate 3**: A circle can be drawn with any centre and any radius.
**Postulate 4**: All right angles are equal to one another.
**Postulate 5** (the famous one): If a straight line falling on two straight lines makes the interior angles on the same side together less than two right angles (180°), then the two lines, if produced indefinitely, meet on that side on which the angles are less than two right angles.
These 5 statements are the seeds. Everything else in classical geometry grows from them.
**Postulate 2**: A terminated line (segment) can be produced indefinitely (extended).
**Postulate 3**: A circle can be drawn with any centre and any radius.
**Postulate 4**: All right angles are equal to one another.
**Postulate 5** (the famous one): If a straight line falling on two straight lines makes the interior angles on the same side together less than two right angles (180°), then the two lines, if produced indefinitely, meet on that side on which the angles are less than two right angles.
These 5 statements are the seeds. Everything else in classical geometry grows from them.
Master this chapter in 30 minutes a day.
Don't just memorise the answer — build a daily practice habit.
Practice 5 Similar Questions Free →All Introduction to Euclid's Geometry practice questions
More Class 9 Introduction to Euclid's Geometry practice
A statement accepted as true without proof and used as a starting point for reasoning is…If a, b, c are points such that a = b and b = c, then a = c. The relation of equality…Which is the correct distinction between an axiom and a postulate as taught in this…Which statement is CORRECT about Euclid's fifth postulate?Two distinct intersecting lines in a plane have exactly how many points in common?