5 Tricky Area of Triangle Questions for Primary 5
- AGrader Learning Centre
- May 8
- 4 min read
Understanding the area of a triangle is an important skill in Primary 5 Mathematics. However, some area of triangle questions can be a little tricky, especially when additional shapes, common bases, or hidden heights are involved! In this guide, we'll take you through a walkthrough of 5 tricky area of triangle questions that challenge even the most confident learners. Along the way, we'll also revisit important concepts such as the height of the triangle, base height, and different triangle formula methods like Heron's formula.
Let's dive into these interesting examples and make calculating the area of a triangle much easier and more enjoyable!
Table of Content:
Important Tips for Solving Primary 5 Area of Triangle Questions
Before we get into the questions, here are some essential tips you should always remember:
The base is always one of the sides of the triangle.
The height of the triangle is always perpendicular to its base.
Area of Triangle Formula:
Question 1: Finding the Shaded Area with Common Height
The rectangle below has a breadth of 16 cm and a length of 24 cm. There are three identical triangles inside the rectangle, each having a height of 8 cm. Find the shaded area.
Tip:
Since the triangles have a common height, total area of 3 triangles = 12 × Total Base × Height
Solutions:
Area of rectangle →24 cm × 16 cm = 384 cm²
Area of 3 triangles → 12 × 24 cm × 8 cm = 96cm²
Shaded area → 384 cm² – 96 cm² = 288 cm²
Answer:
The shaded area is 288 cm².
This question emphasises the importance of correctly identifying when triangles share a common height — a handy skill in mastering area of triangle primary 5 topics.
Question 2: Area of a Triangle Inside a Square
In the figure below, PQRS is a square, and O is the centre of the square. The length of QS (a diagonal) is 18 cm. Find the area of triangle QRS.
Tip:
Remember that in a square, the distance from the centre to any corner is the same! This helps us find the base and height easily.
Solution:
Answer:
The area of triangle QRS is 81 cm².
This question demonstrates how understanding the properties of squares simplifies primary 5 area of triangle questions considerably.
Question 3: Area Relationships Between Triangles and Rectangles
The figure below shows rectangle ABCD and triangle EDC. The area of triangle EDC is 65 cm². Find the area of rectangle ABCD.
Tip:
Notice how the shaded and unshaded areas relate — they're equal! This is a key insight to solve the problem quickly.
Solution:
Answer:
The area of rectangle ABCD is 130 cm².
Understanding how shapes share space within a figure is crucial in being able to calculate the area quickly.
Question 4: Using Heron's Formula to Find the Area
In the figure, ABD and CFE are identical right-angled triangles. The total area of the shaded parts is 82 cm2. Find the area of the unshaded part.
Tip:
Since triangles ABD and CFE are identical and they share the same unshaded area, the shaded area will be 2 equal parts.
Solution:
Answer:
The area of the unshaded part is 29 cm2.
Question 5: Area of an Equilateral Triangle
The figure below is made up of a square ABCD of area 100 cm2 and two identical triangles AED and ADG. DF = FC and AF = FG.
Find the area of the figure.
Tip:
If AF = FG, it means that △ADF and △DFG share the same base and height.
Solutions:
Practice is the key! The more you engage with different types of area of the triangle questions, the faster and better you'll become at solving them!
Ready to master even more exciting Math topics? Keep practising, stay curious, and you’ll soon be a pro at solving any primary 5 area of triangle questions that come your way!
For parents of Primary 5 students, enrolling in AGrader Tuition Centre's Primary Math Programme offers a vital advantage during this critical academic stage. At AGrader, every Primary Math lesson is carefully curated and meticulously planned to stay ahead of the latest MOE syllabus, ensuring students are not just keeping up, but progressing confidently beyond classroom expectations.
Our P5 students benefit from structured weekly lessons taught ahead of school schedules, supported by high-quality, in-house curated worksheets that sharpen problem-solving skills and deepen conceptual understanding. Beyond the classroom, AGrader provides complimentary access to the EverLoop Improvement System, empowering students to revisit and master content from up to three previous academic levels—a unique advantage that reinforces foundational knowledge and boosts exam readiness. With no hidden charges and a strong emphasis on systematic progress, AGrader equips your child to approach Primary 6 and PSLE with confidence and competence.
Give your child the head start they deserve—enrol them at AGrader today and set the stage for future academic success!
Join Our AGrader Community Today! (Free for all AGrader & Non-AGrader students)
Join our Telegram and WhatsApp channels to gain access to more study tips, free downloads, and much more for all subjects.
- WhatsApp channel: https://bit.ly/agwachannel
- Telegram channel: https://bit.ly/agtelchannel
Feel free to explore more related topics in this section:
Comments