Samacheer Kalvi Class 4 Maths Solutions Term 2 Chapter 1 Geometry Exercise 1.3

A. Which of the following figure is symmetrical about dotted line?

Question 1. Observe the figure of the letter 'P' with a vertical dotted line through its stem.
Answer: No. The letter 'P' is not symmetrical along the vertical dotted line shown through its stem. If you fold it along this line, the curved part on the right would not match the straight stem on the left. The letter P does not have this specific line of symmetry.
In simple words: No, the letter 'P' is not symmetrical along the dotted line. If you fold it there, the parts will not match.

🎯 Exam Tip: To check for line symmetry, imagine folding the figure along the given line. If both halves perfectly match, it is symmetrical.

Question 2. Observe the figure of a square with a diagonal dotted line.
Answer: Yes. A square is symmetrical along its diagonals. When folded along a diagonal line, both parts match perfectly. This type of symmetry helps in understanding balanced shapes and their geometric properties.
In simple words: Yes, a square is symmetrical along its diagonal lines. The two parts perfectly match if folded.

🎯 Exam Tip: Remember that squares have four lines of symmetry: two bisecting opposite sides and two along the diagonals.

Question 3. Observe the figure of a four-petal flower shape with a vertical dotted line through its center.
Answer: Yes. The flower shape shown is symmetrical along the vertical dotted line. If you fold the shape along this line, the left and right sides will perfectly overlap. Symmetry is often found in nature, like in the structure of many flowers and leaves.
In simple words: Yes, this flower shape is symmetrical. The two halves match if you fold it on the dotted line.

🎯 Exam Tip: Many natural objects like leaves and flowers show beautiful examples of line symmetry.

Question 4. Observe the figure of the letter 'T' with a horizontal dotted line through its middle.
Answer: No. The letter 'T' is not symmetrical along a horizontal line. If you fold it horizontally, the top bar would not match the vertical stem below it. The letter 'T' has vertical symmetry, but not horizontal symmetry.
In simple words: No, the letter 'T' is not symmetrical if you fold it horizontally. The top and bottom parts would not line up.

🎯 Exam Tip: A letter can have different types of symmetry. 'T' has vertical symmetry, but not horizontal symmetry.

Question 5. Observe the figure of a circle with a diameter as a dotted line.
Answer: Yes. A circle is perfectly symmetrical along any line that passes through its center, which is called a diameter. When folded along a diameter, both halves of the circle will match exactly. Every diameter is a line of symmetry for a circle, showing its perfect balance.
In simple words: Yes, a circle is symmetrical along the dotted line. Any line through the center of a circle is a line of symmetry.

🎯 Exam Tip: A circle has an infinite number of lines of symmetry, as any line passing through its center is a line of symmetry.

Who Am I:

Question 1. I have no sides, no vertices, and many lines of symmetry. Who am I?
Answer: Circle. A circle is a perfectly round shape with no straight edges (sides) or corners (vertices). Any line passing through its center is a line of symmetry, meaning it has an infinite number of them.
In simple words: It is a circle. A circle is round, has no corners or straight edges, and can be folded perfectly in many ways.

🎯 Exam Tip: Remember that "many lines of symmetry" often implies "infinite lines of symmetry" for shapes like a circle.

Question 2. I have 4 equal sides and 4 lines of symmetry. Who am I?
Answer: Square. A square has four sides that are all the same length. It also has four lines of symmetry: two that cut through the middle of opposite sides, and two that go through its diagonals. This combination of properties makes it a highly symmetrical shape.
In simple words: It is a square. A square has four equal sides and four ways you can fold it to make both sides match.

🎯 Exam Tip: Clearly distinguish between the properties of a square and a rectangle, especially regarding side lengths and the number of lines of symmetry.

Question 3. I have 3 equal sides, 3 vertices and 3 lines of symmetry, who am I?
Answer: Equilateral triangle. An equilateral triangle is special because all three of its sides are equal in length, and all three of its angles are equal. It also has three vertices (corners) and three lines of symmetry, each passing from a vertex to the midpoint of the opposite side. This balance makes it very stable.
In simple words: It is an equilateral triangle. All three sides are the same length, and you can fold it in three different ways so the halves match.

🎯 Exam Tip: An equilateral triangle is the most symmetrical type of triangle. Make sure not to confuse its properties with other triangles like isosceles or scalene triangles.

Question 4. I have 4 sides, opposite sides are equal, and I have 2 lines of symmetry. Who am I?
Answer: Rectangle. A rectangle has four sides, where the opposite sides are equal in length and parallel. It has two lines of symmetry, one horizontal and one vertical, both passing through the midpoints of its opposite sides. These lines help balance the shape.
In simple words: It is a rectangle. A rectangle has four sides where opposite sides are equal. You can fold it in two ways for perfect symmetry.

🎯 Exam Tip: Remember that a rectangle has only two lines of symmetry (through the midpoints of its sides), unlike a square which has four.