Triangle Class 10th
Congruent – Polygons in which all sides or angles are equal to those of another polygon are called congruent polygons.
congruent-
Similar figures – Polygons that are similar in shape but differ in size.
Note – All congruent polygons are similar, but not all similar polygons are congruent.
All circles, equilateral triangles, and squares are similar figures.
Equiangular triangles – If the three angles of one triangle are equal to the three angles of another triangle, they are called equiangular triangles.
All equiangular triangles are similar.
Similar triangles – Triangles whose corresponding angles are equal and whose corresponding sides are in the same ratio (i.e., the sides are proportional).
Q. 1. Fill in the blanks –
1. All circles are similar. (Congruent / Similar)
2. All squares are similar. (Congruent / Similar)
3. All equilateral triangles are similar. (Isosceles / Equilateral)
4. Two polygons with the same number of sides are similar if their corresponding angles are equal and their corresponding sides are proportional. (Equal / Proportional)
Q. 2. Give two different examples for each of the following pairs –
1. Examples of similar figures –
- Any two circles (with different radii).
- Any two squares (with different side lengths).
2. Figures that are not similar (non-similar figures) –
- An equilateral triangle and a scalene triangle.
- A rectangle and a rhombus.
Q. 3. State whether the following quadrilaterals are similar or not –
Ans. No, these quadrilaterals are not similar.
