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Chapter 9 of 28
Flashcards

Triangles

ICSE · Class 9 · Mathematics

Flashcards for Triangles — ICSE Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

45 questions25 flashcards5 concepts
25 Flashcards
Card 1Basic Definitions

What is a triangle and what are its basic components?

Answer

A triangle is a plane figure bounded by three straight line segments. Every triangle has: • Three vertices (corner points) • Three sides (line segments) • Three angles (interior angles) Example: In tr

Card 2Side-Angle Relationship

State the relationship between sides and angles in a triangle.

Answer

In any triangle: • The greater side has a greater angle opposite to it • The greater angle has a greater side opposite to it • If two sides are equal, their opposite angles are also equal • If all sid

Card 3Angle Sum Property

What is the angle sum property of triangles?

Answer

The sum of all three interior angles of any triangle is always 180°. Mathematically: ∠A + ∠B + ∠C = 180° This is one of the most fundamental properties of triangles and applies to all types of trian

Card 4Exterior Angle Property

State the exterior angle property of triangles.

Answer

When one side of a triangle is extended, the exterior angle formed is equal to the sum of the two interior opposite angles. Example: If side BC of triangle ABC is extended to D, then: Exterior angle

Card 5Median

What is a median of a triangle and what are its properties?

Answer

A median is a line segment joining a vertex to the midpoint of the opposite side. Properties: • Every triangle has 3 medians • All medians are concurrent (meet at one point) • The point of concurrenc

Card 6Altitude

What is an altitude of a triangle and what are its properties?

Answer

An altitude is the perpendicular distance from a vertex to the opposite side (or its extension). Properties: • Every triangle has 3 altitudes • All altitudes are concurrent (meet at one point) • The

Card 7Congruent Triangles

Define congruent triangles.

Answer

Two triangles are congruent if they have exactly the same shape and size. This means: • All corresponding sides are equal • All corresponding angles are equal • One triangle can be placed exactly over

Card 8Congruency Conditions

State the SSS congruency condition.

Answer

SSS (Side-Side-Side): If three sides of one triangle are equal to three sides of another triangle, then the triangles are congruent. Example: In triangles ABC and DEF: If AB = DE, BC = EF, and AC = D

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Frequently Asked Questions

What are the important topics in Triangles for ICSE Class 9 Mathematics?

Triangles covers several key topics that are frequently asked in ICSE Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

There are 25 flashcards for Triangles covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

Sources & Official References

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