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Chapter 15 of 22
Flashcards

Triangles

ICSE · Class 6 · Mathematics

Flashcards for Triangles — ICSE Class 6 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

92 questions28 flashcards5 concepts

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28 Flashcards
Card 1Interior Angles of a Triangle

In a triangle, two angles are 50° and 60°. Find the third angle.

Answer

Step 1: Sum of all angles in a triangle = 180° Step 2: Add given angles → 50° + 6or 60° = 110° Step 3: Subtract from 180° → 180° − 110° = 70° Answer: The third angle is 70°.

Card 2Right-Angled Triangle

One angle of a triangle is 90°, and another is 35°. What is the measure of the third angle?

Answer

Step 1: Sum of angles = 180° Step 2: One angle is 90° (right angle), second is 35° Step 3: 90° + 35° = 125° Step 4: 180° − 125° = 55° Answer: The third angle is 55°.

Card 3Exterior Angle Property

An exterior angle of a triangle is 120°, and one of the opposite interior angles is 45°. Find the other opposite interior angle.

Answer

Step 1: Exterior angle = sum of two opposite interior angles Step 2: 120° = 45° + x Step 3: x = 120° − 45° = 75° Answer: The other opposite interior angle is 75°.

Card 4Interior Angles with Variables

In triangle ABC, ∠A = 40°, ∠B = x, ∠C = 2x. Find the value of x.

Answer

Step 1: Sum of angles = 180° Step 2: 40° + x + 2x = 180° Step 3: 40° + 3x = 180° Step 4: 3x = 140° → x = 140° / 3 ≈ 46.67° Answer: x ≈ 46.67°

Card 5Exterior Angle Property

The exterior angle of a triangle is 100°. If the two interior opposite angles are equal, what is each of them?

Answer

Step 1: Exterior angle = sum of two opposite interior angles Step 2: Let each angle = x → x + x = 100° Step 3: 2x = 100° → x = 50° Answer: Each interior opposite angle is 50°.

Card 6Types of Triangles by Angles

In a triangle, one angle is 30°, another is 70°. Is the triangle acute, obtuse, or right-angled?

Answer

Step 1: Find third angle → 180° − (30° + 70°) = 80° Step 2: All angles: 30°, 70°, 80° — all less than 90° Step 3: Since all angles are acute, it is an acute-angled triangle. Answer: Acute-angled trian

Card 7Types of Triangles by Angles

One angle of a triangle is 100°. What type of triangle is it?

Answer

Step 1: One angle is 100°, which is greater than 90° Step 2: An angle > 90° is obtuse Step 3: A triangle with one obtuse angle is an obtuse-angled triangle Answer: Obtuse-angled triangle.

Card 8Angle Sum Property

Can a triangle have two right angles? Why or why not?

Answer

Step 1: One right angle = 90° Step 2: Two right angles = 90° + 90° = 180° Step 3: Sum of all three angles in a triangle = 180° Step 4: So, third angle would be 0°, which is not possible Answer: No, a

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Frequently Asked Questions

What are the important topics in Triangles for ICSE Class 6 Mathematics?
Triangles covers several key topics that are frequently asked in ICSE Class 6 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Triangles — ICSE Class 6 Mathematics?
Understand the core concepts first, then work through the 92 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Triangles?
There are 28 flashcards for Triangles covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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