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