Triangles — Chapter Summary
ICSE · Class 9 · Mathematics
Summary of Triangles for ICSE Class 9 Mathematics. Key concepts: A triangle is a plane figure, The greater side has and The median of a triangle.
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Overview
A triangle is a plane figure bounded by three straight line segments. It has three sides and three vertices. The chapter builds understanding of how sides and angles are related, how medians and altitudes meet at special points, how angle properties work, and how triangle congruence is proved using
Key Concepts
A triangle is a plane figure
A triangle is a plane figure bounded by three straight line segments. It has three vertices and three sides. Triangle ABC is the standard example, wit
The greater side has the greater
The greater side has the greater angle opposite to it. If all angles are different, then the sides are also different, and the greater angle has the g
The median of a triangle corresponding
The median of a triangle corresponding to any side is the line joining the mid-point of that side with the opposite vertex. A triangle has three media
The centroid is the point where
The centroid is the point where the three medians meet. It divides each median in the ratio 2:1. For triangle ABC with centroid G and mid-points D, E,
An altitude of a triangle corresponding
An altitude of a triangle corresponding to any side is the length of the perpendicular drawn from the opposite vertex to that side. A triangle has thr
Learning Objectives
- Identify a triangle, its sides, and its vertices
- Understand the relation between unequal sides and unequal angles
- Use the properties of isosceles and equilateral triangles
- Define and use median, centroid, altitude, and orthocentre
- Apply the angle sum property of a triangle
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