The figure shows quadrilateral ABCD. AB and DC each carry one arrowhead, and there are no other marks on the figure. What kind of quadrilateral is ABCD?
One pair only: ABCD is a trapezium.
Ans: trapezium
Example 1
The figure shows parallelogram ABCD. AB is 9 centimetres and BC is 5 centimetres. Find the length of DC.
DC = AB = 9 cm
Ans: 9 cm
How to solve it
Read the marks: matching arrowheads show parallel sides, and ticks show equal lengths.
A parallelogram has two pairs of parallel sides, a rhombus also has four equal sides, and a trapezium has exactly one pair.
In the first figure, AB and DC carry matching arrowheads, so they are parallel. AD and BC carry none.
There is only one pair of parallel sides, so ABCD is a trapezium.
When the shape is given, use its property. In parallelogram ABCD, DC is opposite AB, so DC equals AB, 9 centimetres.
Read the marks, then use the property of the given shape.
Practice questions with worked solutions
Question 1 is free to try. The other 10 open in the free trial, each with its full working.
JK, KL, LM and MJ each carry one tick, so JK = KL = LM = MJ
both pairs of opposite sides carry arrowheads, so JKLM is a parallelogram
a parallelogram with four equal sides is a rhombus
Answer: rhombus
For parents
How do you tackle P5 quadrilateral properties questions?
This page teaches the properties of three quadrilaterals named in the Primary 5 Geometry strand: the parallelogram, the rhombus and the trapezium.
What your child learns here
This page teaches the properties of three quadrilaterals named in the Primary 5 Geometry strand: the parallelogram, the rhombus and the trapezium. Your child learns to read the marks on a four-sided figure and to use a property to find a missing length.
A parallelogram has two pairs of parallel sides, and its opposite sides are equal.
A rhombus is a parallelogram with all four sides equal.
A trapezium has exactly one pair of parallel sides.
Matching arrowheads show parallel sides, ticks show equal sides, and a small square shows a right angle.
A shape is named from its marks, not from how it looks or which way it leans.
Does the answer make sense?
A missing side of a parallelogram or rhombus must equal the side opposite it, so your child's answer is a length already shown on the figure. When naming a shape from its marks, two pairs of matching arrowheads allow a parallelogram or rhombus, while exactly one pair means a trapezium.
How to practise these questions
Basic questions train naming each of the three four-sided figures from its markings and using a property to find a missing side. Intermediate questions add claims to judge, where your child must say whether a name fits the marks. Challenge questions combine naming with angles and lengths, or set a parallel pair that does not look parallel at all. When the marks are hard to read, watch that question's solution film and come back to it from Revision later.
Questions parents ask
What is the difference between a rhombus and a parallelogram? Both have two pairs of parallel sides, with opposite sides equal. A rhombus also has all four sides equal.
Can a shape be a parallelogram and a rhombus at once? Yes. Every rhombus is a parallelogram with four equal sides, and a square is a rhombus with four right angles.
Which quadrilaterals are in the Primary 5 syllabus? The Primary 5 Geometry strand lists the properties of the parallelogram, rhombus and trapezium, and finding unknown angles in them without additional construction of lines.
