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Triangles — Flashcards

ICSE · Class 7 · Mathematics

24 flashcards for Triangles (ICSE Class 7 Mathematics) to test yourself on key terms and facts. Sample: "A triangle has angles 48° and 73°. Find"

45 questions24 flashcards8 formulas & key relations5 concepts

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24 Flashcards·
Angle sum propertyAlgebra in triangle anglesExterior angle theoremIsosceles triangle angles
Card 1Angle sum property

A triangle has angles 48° and 73°. Find the third angle.

Answer

Step 1: Add the two known angles: 48° + 73° = 121°. Step 2: Subtract from 180°: 180° - 121° = 59°. Answer: The third angle is 59°.

Card 2Angle sum property

Can a triangle have angles 60°, 70°, and 70°? Show the check.

Answer

Step 1: Add the angles: 60° + 70° + 70° = 200°. Step 2: A triangle’s angles must total 180°. Answer: No, this is not possible because 200° is not 180°.

Card 3Algebra in triangle angles

Three angles of a triangle are (2x + 20)°, (x + 30)°, and (2x - 10)°. Find x and all angles.

Answer

Step 1: Use angle sum property: (2x + 20) + (x + 30) + (2x - 10) = 180° Step 2: Simplify: 5x + 40 = 180° Step 3: Subtract 40°: 5x = 140° Step 4: Divide by 5: x = 28 Step 5: Find angles: (2x + 20) = 2(…

Card 4Exterior angle theorem

In a triangle, one exterior angle is 130° and the two interior opposite angles are 7x and 6x. Find x.

Answer

Step 1: Use exterior angle theorem: 130° = 7x + 6x Step 2: Combine like terms: 130° = 13x Step 3: Divide by 13: x = 10 Answer: x = 10.

Card 5Exterior angle theorem

Using x = 10, find the two interior opposite angles in the previous triangle.

Answer

Step 1: Replace x with 10. Step 2: 7x = 7 × 10 = 70°. Step 3: 6x = 6 × 10 = 60°. Step 4: Check: 70° + 60° = 130°. Answer: The angles are 70° and 60°.

Card 6Isosceles triangle angles

In an isosceles triangle, the vertex angle is 40°. Find each base angle.

Answer

Step 1: The two base angles are equal. Let each be x. Step 2: Use angle sum property: x + x + 40° = 180° Step 3: Simplify: 2x + 40° = 180° Step 4: Subtract 40°: 2x = 140° Step 5: Divide by 2: x = 70° …

Card 7Isosceles triangle angles

One base angle of an isosceles triangle is 65°. Find the vertex angle.

Answer

Step 1: Base angles in an isosceles triangle are equal. Step 2: The other base angle is also 65°. Step 3: Let the vertex angle be x. Step 4: Use angle sum property: x + 65° + 65° = 180° Step 5: Simpli…

Card 8Isosceles triangle angles

In an isosceles triangle, one base angle is double the vertex angle. Find all three angles.

Answer

Step 1: Let the vertex angle be x. Step 2: Each base angle is 2x. Step 3: Use angle sum property: x + 2x + 2x = 180° Step 4: Simplify: 5x = 180° Step 5: Divide by 5: x = 36° Step 6: Find each base ang…

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Frequently Asked Questions

What are the important topics in Triangles for ICSE Class 7 Mathematics?
Key topics in Triangles include Basic Parts of a Triangle, Angles in a Triangle, Classification of Triangles, Isosceles and Equilateral Triangle Properties. Study these first, then practise questions on each for Class 7 exams.
How many flashcards are available for Triangles?
There are 24 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 7 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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