Calculating the area of triangles using the formula ½ × base × height.
Where your child meets this in real life: Calculating the area of a triangular garden bed or sail on a boat
SEAGReady breaks area of triangles into 3 steps, taught in order so each skill builds on the last.
Master right-angled triangles skills
Master triangles with perpendicular height skills
Master word problems skills
Three free sample questions from our area of triangles course. Every question comes with a full explanation, and hints that guide without giving the answer away.
Sean is cutting a rectangular piece of card in half diagonally to make two triangular bookmarks. The card is 10 cm along the bottom and 6 cm tall. What is the area of each triangular bookmark?
Answer: A. 30 cm²
The triangle is half of a rectangle. Base = 10 cm, Height = 6 cm Rectangle area: 10 x 6 = 60 cm² Triangle area: 60 ÷ 2 = 30 cm²
Stuck? Start here: A triangle is half of a rectangle with the same base and height.
Aoife is painting a triangular warning sign. The base of the sign is 40 cm and the perpendicular height from the base to the top is 30 cm. What is the area of the sign?
Answer: A. 600 cm²
Area of triangle = ½ x base x perpendicular height Base = 40 cm, Height = 30 cm 40 x 30 = 1200 cm² 1200 ÷ 2 = 600 cm²
Stuck? Start here: The perpendicular height is the height at right angles to the base.
Sophie wants to plant flowers in a triangular section of her garden. The triangle has a base of 10 metres and a height of 6 metres. Each packet of flower seeds covers 10 m². How many packets of seeds does Sophie need?
Answer: B. 3 packets
Step 1: Find the triangle area ½ x 10 x 6 = 30 m² Step 2: Divide by coverage per packet 30 ÷ 10 = 3 packets
Stuck? Start here: First find the area of the triangular garden.
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Aoife is cutting a rectangular piece of card in half diagonally to make two triangular bookmarks. The card is 8 cm along the bottom and 6 cm tall.
What is the area of each triangular bookmark?
½ × 8 × 6
Step 1 of 4
Aoife is cutting a rectangular piece of card in half diagonally to make two triangular bookmarks. The card is 8 cm along the bottom and 6 cm tall.
What is the area of each triangular bookmark?
Each triangular bookmark has an area of 24 cm².
The key insight: A right-angled triangle is exactly half of a rectangle with the same base and height!
Watch out: 8 × 6 = 48 cm². Forgetting to halve gives you the rectangle area, not the triangle area.
These are the misconceptions we see most often in area of triangles, including the ones our practice questions are specifically designed to catch.
Struggling with area of triangles? The real gap is often in one of these earlier topics.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.