IMO Practice Test — Lines and Angles
6 Questions • 12 min • Olympiad level
12:00
Question 1 of 6
hard
If two lines are perpendicular, what is the angle between them?
45 degrees
90 degrees
180 degrees
360 degrees
Explanation: Perpendicular means meeting at right angles — exactly 90 degrees.
Question 2 of 6
hard
How many pairs of parallel lines does a rectangle have?
1
2
3
4
Explanation: Opposite sides are parallel — top/bottom form one pair, left/right form another. Total: 2 pairs.
Question 3 of 6
hard
Angle A = 35 degrees and Angle B = 55 degrees share a common ray. The total angle formed is:
20 degrees
90 degrees
100 degrees
70 degrees
Explanation: Adjacent angles add up: 35 + 55 = 90 degrees — a right angle!
Question 4 of 6
hard
Which statement about parallel lines is ALWAYS true?
They meet at 90 degrees
They never meet
They form acute angles
They are always horizontal
Explanation: Parallel lines never meet, no matter how far they are extended.
Question 5 of 6
hard
A shape has 4 sides. Opposite sides are parallel. ALL angles are 90 degrees. What could it be?
Square only
Rectangle only
Square or Rectangle
Rhombus
Explanation: Both squares and rectangles have 4 right angles and opposite sides parallel.
Question 6 of 6
hard
If you fold a paper so one edge exactly lies on top of another edge, the fold line is ___ to both edges.
Parallel
Perpendicular
Intersecting
Diagonal
Explanation: The fold line (crease) meets both edges at exactly 90 degrees — it is perpendicular to both.