Geometry
- Triangle: A triangle is a three-sided polygon. It is the polygon with the least number of sides.
We denote this triangle as ΔPQR. Here, are the sides of ΔPQR. The points P, Q and R are the vertices of ΔPQR and the angles are ∠RPQ, ∠PQR and ∠QRP.
- A triangle can be classified on the basis of the measures of its angles and sides.
- Classification of triangles on the basis of the measures of its angles:
Name |
Nature of the angle |
Acute-angled triangle obtuse-angled triangle Right-angled triangle |
Each angle is acute One angle is obtuse One angle is a right angle |
- Classification of triangles on the basis of the lengths of its sides:
Name |
Nature of the angle |
Scalene triangle Isosceles triangle Equilateral triangle |
All three sides are of unequal length Any two sides are of equal length All sides are of equal length |
- Angle sum property of triangles:
The sum of all the three interior angles of a triangle is 180°.
∴ ∠A + ∠B + ∠C = 180°
Exa…
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