PRELIMINARY STAGE 2026
Labone SHS: 41 points (Winner, qualified to the one-eighth stage; won NSMQ Star, Clean Sheet Prize)
Notre Dame Sem. SHS: 39 points (won 800 Ghana Cedis in Goil Riddle Bonanza)
T.I. AMASS, Wa: 3 points
ROUND 5 - RIDDLE
RIDDLE
We are a pair of lines.
However, we have no point in common.
When cut by a transversal, corresponding angles are equal.
ANSWER: Parallel lines
EXPLANATION:
Parallel lines never intersect, so they have no point in common.
When a transversal cuts them, the corresponding angles are equal.
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PRACTICE QUESTIONS
1. RIDDLE:
We are a pair of lines.
We have exactly one point in common.
We meet to form four equal angles.
Each angle between us is a right angle.
The product of our gradients is $-1$.
We are written with the symbol $\perp$.
Who am I?
ANSWER: PERPENDICULAR LINES
EXPLANATION:
Perpendicular lines meet at $90^\circ$.
If neither is vertical, $m_1m_2 = -1$.
2. RIDDLE:
I am a line.
I cross two or more other lines.
I meet each of them at a different point.
I create corresponding, alternate and co-interior angles.
When the lines I cross are parallel, those angles are equal or supplementary.
I am the line that cuts across a pair of parallel lines.
Who am I?
ANSWER: TRANSVERSAL
EXPLANATION:
A transversal crosses two or more lines at different points.
With parallel lines, corresponding and alternate angles are equal and co-interior angles add up to 180°.
3. RIDDLE:
We are a pair of angles.
We are formed by two intersecting lines.
We share a vertex.
We do not share an arm.
We are always equal.
We face each other across the crossing point, like the top and bottom angles of an X.
Who am I?
ANSWER: VERTICALLY OPPOSITE ANGLES
EXPLANATION:
Two intersecting lines form two pairs of vertically opposite angles.
Each pair is equal, since each angle is $180^\circ$ minus the same adjacent angle.
4. RIDDLE:
We are a pair of lines.
We lie in the same plane.
We are not parallel.
We have exactly one point in common.
Where we cross, we form two pairs of vertically opposite angles.
We cross each other at a single point.
Who am I?
ANSWER: INTERSECTING LINES
EXPLANATION:
Two non-parallel lines in a plane meet at exactly one point.
5. RIDDLE:
We are a pair of lines.
We have no point in common.
Yet we are not parallel.
We cannot both lie in one plane.
We only occur in three dimensions.
A line on the floor and a non-parallel line on the ceiling of a room are an example of us.
Who am I?
ANSWER: SKEW LINES
EXPLANATION:
Skew lines neither meet nor are parallel.
This is only possible in three dimensions.
6. RIDDLE:
We are three or more lines.
We lie in the same plane.
We all pass through one point.
The medians of a triangle are an example of us.
So are the perpendicular bisectors of its sides.
We share one common point of intersection.
Who am I?
ANSWER: CONCURRENT LINES
EXPLANATION:
Lines are concurrent when they all pass through one point.
The medians of a triangle are concurrent at the centroid.