Area of Triangle
Half base times height.
Key idea
Half base times height.
In depth
Two identical triangles form a parallelogram, so a triangle’s area is half of base times height: A = ½bh. Any side can be the base, as long as the height is perpendicular to it.
Worked example
Base 8, height 5: A = ½ × 8 × 5 = 20.
Formula
Real-world uses
- Finding the area of a gable end for roofing
- Estimating the size of a triangular sail
Common mistake
Forgetting the ½.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Area of Triangle?
Half base times height. It is a topic at the intermediate level in Geometry.
What is the formula for Area of Triangle?
The key formula is A = ½ b h.
Where is Area of Triangle used in real life?
Real-world examples: Finding the area of a gable end for roofing; Estimating the size of a triangular sail.
What should I learn before Area of Triangle?
Make sure you are comfortable with Area of Parallelogram, the previous topic in Geometry.
What is a common mistake with Area of Triangle?
Forgetting the ½.
How can I practise Area of Triangle?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Area of Triangle?
Move on to Heron’s Formula next.
Related intermediate topics in Geometry
- Vertical Angles – Opposite angles formed by intersecting lines are equal.
- Parallel Lines and Transversals – Corresponding and alternate interior angles are equal.
- Exterior Angle Theorem – An exterior angle equals the sum of the two remote interior angles.
- Triangle Inequality – Any two sides sum to more than the third.
- Congruent Triangles – Same shape and size: SSS, SAS, ASA, AAS, HL.
- Similar Triangles – Same shape, proportional sides: AA, SAS~, SSS~.