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Triangles — Flashcards

Karnataka Board · Class 9 · Mathematics

20 flashcards for Triangles (Karnataka Board Class 9 Mathematics) to test yourself on key terms and facts. Sample: "In triangle ABC, AB = 5 cm, AC = 5 cm.

45 questions20 flashcards5 concepts

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20 Flashcards·
Properties of Isosceles TriangleSAS Congruence RuleASA Congruence RuleArea of TriangleSSS Congruence RuleRight Triangle and PythagorasRHS Congruence Rule
Card 1Properties of Isosceles Triangle

In triangle ABC, AB = 5 cm, AC = 5 cm, and BC = 6 cm. Find the measures of angles B and C.

Answer

Step 1: Identify triangle type → AB = AC, so triangle ABC is isosceles. Step 2: Apply isosceles triangle property → Angles opposite to equal sides are equal, so ∠B = ∠C. Step 3: Let ∠B = ∠C = x. Step …

Card 2SAS Congruence Rule

Prove that triangles ABC and DEF are congruent if AB = DE = 4 cm, BC = EF = 3 cm, and ∠B = ∠E = 90°.

Answer

Step 1: Identify given information → AB = DE = 4 cm, BC = EF = 3 cm, ∠B = ∠E = 90°. Step 2: Check congruence rule → We have two sides and included angle. Step 3: Apply SAS rule → In △ABC and △DEF: AB …

Card 3Properties of Isosceles Triangle

In triangle PQR, PQ = 7 cm, QR = 7 cm, and PR = 8 cm. If QS is the altitude to PR, find the length of PS.

Answer

Step 1: Identify triangle type → PQ = QR = 7 cm, so triangle PQR is isosceles. Step 2: Property of isosceles triangle → Altitude from vertex angle bisects the base. Step 3: Since QS is altitude to PR,…

Card 4ASA Congruence Rule

When do you use the ASA congruence rule? Give a worked example.

Answer

Use ASA when: Two angles and included side of one triangle equal two angles and included side of another triangle. Example: In △ABC and △XYZ, if ∠A = ∠X = 60°, ∠B = ∠Y = 50°, and AB = XY = 5 cm. Step …

Card 5Area of Triangle

Solve: In △ABC, AB = AC = 10 cm and BC = 12 cm. Find the area of the triangle.

Answer

Step 1: Identify triangle type → AB = AC, so isosceles triangle. Step 2: Draw altitude AD to BC → D bisects BC, so BD = DC = 6 cm. Step 3: Use Pythagoras in △ABD → AD² + BD² = AB², so AD² + 6² = 10², …

Card 6SSS Congruence Rule

Prove: If two triangles have all three sides equal, they are congruent. State the rule used.

Answer

Step 1: State the rule → SSS (Side-Side-Side) Congruence Rule. Step 2: Given → In △ABC and △DEF: AB = DE, BC = EF, CA = FD. Step 3: Apply SSS rule → Since all three corresponding sides are equal, △ABC…

Card 7Right Triangle and Pythagoras

In right triangle ABC with ∠C = 90°, if AB = 13 cm and BC = 5 cm, find AC and verify using congruence.

Answer

Step 1: Apply Pythagoras theorem → AB² = AC² + BC², so 13² = AC² + 5². Step 2: Calculate AC → 169 = AC² + 25, so AC² = 144, therefore AC = 12 cm. Step 3: Verify dimensions → We have a 5-12-13 right tr…

Card 8RHS Congruence Rule

When do you use RHS congruence rule? Solve: Two right triangles have hypotenuse 10 cm and one side 6 cm. Are they congruent?

Answer

Use RHS when: Two right triangles have equal hypotenuse and one equal side. Solution: Step 1: Given → Both triangles have hypotenuse = 10 cm, one side = 6 cm, and one right angle. Step 2: Find third s…

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Frequently Asked Questions

What are the important topics in Triangles for Karnataka Board Class 9 Mathematics?
Key topics in Triangles include Congruence of Triangles - Fundamental Concepts, SAS Congruence Rule - Side-Angle-Side, ASA and AAS Congruence Rules - Angle-Side-Angle and Angle-Angle-Side, SSS Congruence Rule - Side-Side-Side. Study these first, then practise questions on each for Class 9 exams.
How many flashcards are available for Triangles?
There are 20 flashcards for Triangles covering key definitions, facts and ideas. A few sample cards are shown on this page.
How should I revise Triangles for Class 9 exams?
Learn the core ideas first, then work through the 45 practice questions on Triangles. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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