Heron's Formula
Heron's formula gives the area of a triangle when the lengths of all three sides are known.
Practice This ConceptMain explanation
Teacher explanation
When perpendicular height is not given, first find the semi-perimeter, then use the product involving the three side differences. It is especially useful for scalene triangles.
Example
For sides 13 cm, 14 cm, and 15 cm, s = 21 cm and area = √(21 × 8 × 7 × 6) = 84 cm².
Simple analogy
Heron's formula starts with half the boundary.
Common confusion
Students sometimes use the full perimeter in place of semi-perimeter s.
Exam tip
Write s = (a + b + c)/2 clearly before applying the square-root formula.
Study the heron's formula diagram carefully
Use the labelled diagram to keep heron's formula clear in short answers and revision.
What this diagram makes clear
This diagram keeps the labels and direction of heron's formula in the right order.
Where this helps in exams
Use this for labelled diagram work and short exam answers on heron's formula.
Revision cue
Revise heron's formula through the labels before writing the answer.
Answer writing and exam use
1-mark use
Write the exact meaning of heron's formula in one clean line.
2-mark use
Define heron's formula and add one example or condition.
3-mark use
Explain heron's formula, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.
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