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Heron's Formula — Flashcards

Gujarat Board · Class 9 · Mathematics

20 flashcards for Heron's Formula (Gujarat Board Class 9 Mathematics) to test yourself on key terms and facts.

45 questions20 flashcards3 formulas & key relations4 concepts

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20 Flashcards·
Introduction and HistoryFormulaSemi-perimeterApplicationsSolved ExamplesSpecial Triangles
Card 1Introduction and History

What is Heron's Formula and who discovered it?

Answer

Heron's Formula (also called Hero's Formula) was discovered by Heron of Alexandria around 10 AD. It calculates the area of a triangle when all three sides are known, without needing to find the height…

Card 2Formula

State Heron's Formula for finding the area of a triangle.

Answer

Heron's Formula: Area = √[s(s-a)(s-b)(s-c)] where: • a, b, c are the three sides of the triangle • s is the semi-perimeter = (a+b+c)/2 • The result gives the area in square units…

Card 3Semi-perimeter

What is semi-perimeter? How do you calculate it?

Answer

Semi-perimeter (s) is half of the perimeter of a triangle. Formula: s = (a+b+c)/2 where a, b, c are the three sides of the triangle. Example: If sides are 6 cm, 8 cm, 10 cm, then s = (6+8+10)/2 = 12 c…

Card 4Applications

When is Heron's Formula most useful?

Answer

Heron's Formula is most useful when: • All three sides of a triangle are known • The height of the triangle is difficult to calculate • You cannot easily identify a base and corresponding height • Wor…

Card 5Solved Examples

Find the area of a triangle with sides 3 cm, 4 cm, and 5 cm using Heron's Formula.

Answer

Given: a = 3 cm, b = 4 cm, c = 5 cm Step 1: Calculate semi-perimeter s = (3+4+5)/2 = 6 cm Step 2: Apply Heron's Formula Area = √[s(s-a)(s-b)(s-c)] = √[6(6-3)(6-4)(6-5)] = √[6×3×2×1] = √36 = 6 cm²…

Card 6Solved Examples

A triangular park has sides 40 m, 32 m, and 24 m. Find its area using Heron's Formula.

Answer

Given: a = 40 m, b = 32 m, c = 24 m Step 1: s = (40+32+24)/2 = 48 m Step 2: s-a = 48-40 = 8 m s-b = 48-32 = 16 m s-c = 48-24 = 24 m Step 3: Area = √[48×8×16×24] = √[147456] = 384 m² Note: This is a ri…

Card 7Special Triangles

Find the area of an equilateral triangle with side 10 cm using Heron's Formula.

Answer

Given: All sides = 10 cm (a = b = c = 10) Step 1: s = (10+10+10)/2 = 15 cm Step 2: s-a = s-b = s-c = 15-10 = 5 cm Step 3: Area = √[15×5×5×5] = √[1875] = 25√3 cm² ≈ 25×1.732 = 43.3 cm²…

Card 8Solved Examples

Two sides of a triangle are 8 cm and 11 cm, and the perimeter is 32 cm. Find the area.

Answer

Given: a = 8 cm, b = 11 cm, Perimeter = 32 cm Step 1: Find third side c = 32 - (8+11) = 13 cm Step 2: s = 32/2 = 16 cm Step 3: s-a = 8, s-b = 5, s-c = 3 Step 4: Area = √[16×8×5×3] = √[1920] = 8√30 cm²…

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Frequently Asked Questions

What are the important topics in Heron's Formula for Gujarat Board Class 9 Mathematics?
Key topics in Heron's Formula include Introduction to Heron's Formula, Step-by-Step Application, Worked Examples and Applications, Special Cases and Variations. Study these first, then practise questions on each for Class 9 exams.
How many flashcards are available for Heron's Formula?
There are 20 flashcards for Heron's Formula covering key definitions, facts and ideas. A few sample cards are shown on this page.
How should I revise Heron's Formula for Class 9 exams?
Learn the core ideas first, then work through the 45 practice questions on Heron's Formula. Revise definitions regularly and use flashcards for quick recall before the exam.

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