Samacheer Kalvi Class 6 Maths Solutions Term 2 Chapter 4 Geometry Exercise 4.1

Tamilnadu Samacheer Kalvi 6th Maths Solutions Term 2 Chapter 4 Geometry Ex 4.1

Question 1. Fill in the blanks.
(a) Every triangle has at least _______ acute angles.
(b) A triangle in which none of the sides equal is called a _______.
(c) In an isosceles triangle _______ angles are equal.
(d) The sum of three angles of a triangle is _______.
(e) A triangle with two equal sides is called _______ angled triangle.

Answer:
(a) Two
(b) Scalene Triangle
(c) Two
(d) \(180^\circ\)
(e) Isosceles right-angled triangle
In simple words: These blanks cover basic facts about triangles. Every triangle has at least two acute angles, a scalene triangle has no equal sides, and an isosceles triangle has two equal angles. All angles in any triangle always add up to 180 degrees. An isosceles triangle with a right angle is called an isosceles right-angled triangle.

🎯 Exam Tip: Remember to clearly state the type of triangle based on its side or angle properties when filling in blanks.

Question 2. Match the following
(i) No sides are equal - Isosceles triangle
(ii) One right angle - Scalene triangle
(iii) One obtuse angle - Right angled triangle
(iv) Two sides of equal length - Equilateral triangle
(v) All sides are equal - Obtuse angled triangle

Answer:
(i) No sides are equal - Scalene triangle
(ii) One right angle - Right-angled triangle
(iii) One obtuse angle - Obtuse angled triangle
(iv) Two sides of equal length - Isosceles triangle
(v) All sides are equal - Equilateral triangle
In simple words: This exercise matches triangle types with their key features. For example, if no sides are equal, it's a scalene triangle. If all sides are equal, it's an equilateral triangle. Knowing these definitions helps you quickly identify triangles.

🎯 Exam Tip: Memorize the definitions of different triangles based on both their sides (scalene, isosceles, equilateral) and their angles (acute, right, obtuse) to match correctly.

Question 3. In ∆ABC, name the
a) Three Sides: _______, _______, _______
b) Three Angles: _______, _______, _______
c) Three Vertices: _______, _______, _______

Answer:
(a) Three Sides: \( \overline{\mathrm{AB}}, \overline{\mathrm{BC}}, \overline{\mathrm{CA}} \)
(b) Three Angles: \( \angle \mathrm{ABC}, \angle \mathrm{BCA}, \angle \mathrm{CAB} \) or \( \angle \mathrm{A}, \angle \mathrm{B}, \angle \mathrm{C} \)
(c) Three Vertices: A, B, C
In simple words: A triangle has three main parts: sides, angles, and vertices. The sides are the lines connecting the corners. The angles are the spaces formed inside the corners, and the vertices are the corner points themselves. Each part helps define the triangle's shape.

🎯 Exam Tip: When naming sides, use a bar above the two vertex letters (e.g., \( \overline{\mathrm{AB}} \)). For angles, you can use a single vertex letter (e.g., \( \angle \mathrm{A} \)) or three letters with the vertex in the middle (e.g., \( \angle \mathrm{CAB} \)).

Question 4. Classify the given triangles based on its sides as scalene, isosceles or equilateral.
(i)