RBSE Solutions Class 5 Maths Chapter 16 Geometry More Ques

Page No. 86

Question 1. With the help of pencils explain angles by one fourth round, half round and complete round.
Answer: Imagine holding two pencils together, one on top of the other. Now, if you keep one pencil still and rotate the other:
- **One fourth round:** When the rotating pencil turns a quarter of a full circle, it makes a right angle, which is 90 degrees. It looks like an 'L' shape.
- **Half round:** When the rotating pencil turns half a full circle, it makes a straight angle, which is 180 degrees. The two pencils now point in opposite directions along a straight line.
- **Complete round:** When the rotating pencil turns a full circle, it makes a complete angle, which is 360 degrees, returning to its starting position. These movements help us understand different types of angles in our daily life.
In simple words: Start with two pencils together. When you turn one pencil a quarter way around, it makes a 90-degree angle. Turn it half way for a 180-degree straight line. Turn it all the way around for a full 360-degree circle.

🎯 Exam Tip: Visualizing angles with real-world objects like pencils or clock hands helps in understanding rotation and angle concepts better.

Page No. 87

Question 1. Explain the concept of right angle on the basis of folding a paper.
Answer: To understand a right angle using paper folding, follow these steps:
1. Take a square piece of paper.
2. Fold the paper exactly in half, making sure all the edges meet perfectly.
3. Now, fold the paper in half again in the same direction, making another careful crease.
4. When you open the paper, you will see two lines crossing each other where you made the folds. These intersecting lines form four perfect square corners. Each of these corners is a right angle, measuring 90 degrees. This method clearly shows how a right angle is formed and what it looks like.
In simple words: Take a square paper and fold it in half, then fold it in half again. When you open the paper, the creases will show you four perfect square corners, which are all right angles.

🎯 Exam Tip: Remember that a right angle always measures 90 degrees and looks like the corner of a square or a book. Always use precise folds to get accurate angles.

Page No. 90

Practice Work

Question 1. Identify all the angles of the following geometrical shapes. Mark them as acute angle, right angle and obtuse angle.
Answer: Based on the provided solution, here are the vertices that represent each type of angle within various geometrical shapes:
1. **Acute angle vertices (corner):** A, B, C, D, E, M, V. These angles are sharp and smaller than a right angle, measuring less than 90 degrees.
2. **Right angle vertices:** F, G, H, I, J, T, U. These angles form perfect square corners, measuring exactly 90 degrees.
3. **Obtuse angle vertices:** K, L, N, O, P, Q, R, S, W. These angles are wide and larger than a right angle, measuring more than 90 degrees.
In simple words: The solution lists specific points (vertices) on different shapes. Pointy corners are acute angles, square corners are right angles, and wide corners are obtuse angles.

🎯 Exam Tip: When identifying angles, compare them to a known right angle (like the corner of a book). If it's smaller, it's acute; if it's larger, it's obtuse.

Question 1. A semicircular tool is given in your geometry box (Drawing box). What is that called ? and why it is used?
Answer: The semicircular tool found in your geometry box (also called a drawing box) is known as a **protractor**. It is primarily used for **measuring angles** and **drawing angles** of specific degrees. A typical protractor is shaped like a half-circle, marked with measurements from 0 to 180 degrees. It also has a straight base line with a mark at 90 degrees, indicating a right angle. This tool helps us accurately determine the size of any given angle.
In simple words: The half-moon shaped tool in your geometry box is called a protractor. We use it to measure how big an angle is, usually in degrees, and to draw angles.

🎯 Exam Tip: Always align the protractor's base line with one side of the angle and its center mark with the angle's vertex for accurate measurement.