Chapter 18 of RD Sharma Class 6 Maths – Basic Geometrical Tools – introduces students to the essential instruments used in geometry, laying the foundation for accurate construction and measurement. Geometry isn’t just about shapes; it’s about precision, and to achieve that, students must first become familiar with tools like the ruler, compass, divider, protractor, set squares, and pencil.
Each tool serves a specific purpose—for example, a ruler is used to draw and measure straight lines, a compass helps in drawing arcs and circles, while a protractor measures angles. This chapter not only explains the function of each instrument but also teaches how to handle them correctly through practical examples and exercises. Mastering these tools is a key skill for future geometry topics and helps students build accuracy and confidence in constructions and diagrams.
Geometry is one of the most practical and visual branches of mathematics, and mastering it begins with understanding the basic geometrical tools. In Chapter 18 of RD Sharma Class 6 Maths, students are introduced to the essential instruments used for constructing and analyzing different geometric figures. These tools are not just classroom objects—they are the building blocks for accurate drawing, measuring, and understanding shapes in both academic and real-life contexts.
Geometrical tools are instruments used to create shapes like triangles, circles, squares, parallelograms, and hexagons—shapes that we observe every day in architecture, art, and nature. Each shape has its own unique features such as length, breadth, radius, and angles, and to draw them precisely, students must know how to use tools like the ruler, compass, protractor, divider, and set-squares.
These tools not only simplify the process of drawing complex shapes but also help students gain a deeper understanding of concepts like symmetry, angles, radius, and perimeter.
The RD Sharma solutions for Class 6 Chapter 18 explain the usage of each tool with well-structured examples, illustrations, and exercises. These solutions encourage concept clarity, enhance problem-solving speed, and help students learn how to apply their geometric knowledge effectively.
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Whether you're trying to understand how to use a compass correctly or wondering how to measure an angle precisely, this chapter lays the perfect groundwork. Download the RD Sharma Chapter 18 Solutions today, and start your journey towards mastering geometry.
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1. Define geometrical tools and explain why accuracy is important in geometric constructions.
Geometrical tools are instruments like rulers, compasses, protractors, dividers, and set-squares used to draw and measure geometric shapes. Accuracy is crucial because even a small mistake can lead to incorrect measurements, which affects the integrity of the shape and the solution of the problem.
2. What is the primary function of a compass in geometry, and how is it used correctly?
A compass is used to draw arcs and circles. To use it correctly, place the pointed leg on the center of the circle and adjust the pencil leg to the desired radius. Rotate the compass steadily to complete the arc or circle.
3. Explain how a protractor is used to construct an angle of 135°.
Place the center of the protractor on the vertex of the angle and align the baseline with one arm. Mark a point at 135° on the scale and join it to the vertex. This forms an angle of 135°.
4. What is the difference between a divider and a compass? How are they used differently?
A compass is used for drawing circles or arcs, while a divider is used to compare lengths or mark equal distances. The divider has two pointed legs, whereas the compass has one pointed leg and one with a pencil.
5. Which geometrical tool would you use to draw a perfect right angle? Explain.
A set-square (particularly the 45°–45° or 30°–60° set-square) is ideal for drawing a right angle. Place one edge along a baseline and use the perpendicular edge to draw the 90° angle.
6. How do you use a ruler and compass together to construct a perpendicular bisector?
Draw a line segment with the ruler. Using a compass set to more than half the length, draw arcs above and below from each endpoint. The intersection points are joined to form the perpendicular bisector.
7. How would you measure an angle of 100° using a protractor?
Place the center of the protractor on the angle’s vertex, align the baseline with one arm, and mark a point at 100° on the outer scale. Connect this point to the vertex to complete the angle.
8. A student needs to construct a triangle with one side 6 cm and angle 60°. Which tools are required?
A ruler (to draw the 6 cm side), protractor (to measure and draw the 60° angle), and compass (to construct remaining sides if needed) are required.
9. Can a protractor be used to draw an angle without a base line? Why or why not?
No. A baseline is essential to align the protractor correctly. Without it, the angle cannot be measured or constructed accurately.
10. How do you mark equal distances using a divider?
Adjust the divider legs to the required distance. Then step off this length repeatedly along a line or arc to mark equal intervals.
11. What is the significance of the center hole in a protractor?
The center hole is placed on the vertex of the angle to align the baseline accurately for measurement or construction of angles.
12. Explain the steps to draw a 60° triangle using only a ruler and compass.
13. Can a set-square be used to measure 75°? Why or why not?
No. Standard set-squares measure 30°, 45°, 60°, and 90°. To get 75°, you must combine angles using a protractor or use geometric construction methods.
14. Why is it important to sharpen the pencil in your compass?
A sharpened pencil ensures clear, precise arcs and circles, reducing errors and maintaining accuracy in geometry work.
15. Describe how to verify if an angle drawn with a protractor is accurate.
After drawing, re-place the protractor on the vertex and baseline. Check if the other arm aligns exactly at the intended degree mark (e.g., 90°, 120°, etc.).
16. What tool would you use to divide a line segment into 5 equal parts? Explain the process briefly.
Use a divider to step off equal segments or a ruler and draw an auxiliary line at an angle. Mark 5 equal divisions, connect the last to the segment’s endpoint, and draw parallels using a set-square to divide the original segment.
17. How do set-squares help in drawing parallel lines?
Align one set-square on the base line and slide the other along its edge, maintaining alignment. Draw lines using the moving set-square to get perfectly parallel lines.
18. Which tool would you use to verify if a triangle is equilateral, and how?
Use a ruler to measure all sides (they should be equal) and a protractor to verify all angles are 60°.
19. Name the tool best suited to copy a given angle onto another location and describe the steps.
A compass is best.
20. Explain how mastering geometrical tools helps in real-life applications.
Knowing how to use geometric tools improves visual-spatial reasoning, which is vital in architecture, engineering, design, and robotics. It also strengthens accuracy and logical thinking, which are useful in everyday problem-solving.
Basic geometrical tools are essential instruments used to draw and measure geometric figures. According to RD Sharma Class 6 Chapter 18, tools like the ruler, compass, protractor, divider, and set-squares are introduced to help students construct accurate shapes such as lines, angles, circles, and triangles.
Understanding geometrical tools in Class 6 lays the foundation for accurate drawing and problem-solving in geometry. These tools help students visualize concepts, enhance spatial reasoning, and prepare for more complex geometric constructions in higher classes.
A compass is used to draw arcs and circles and to replicate distances. In RD Sharma Chapter 18, students learn how to use a compass precisely to create geometric shapes and perform constructions like bisecting angles or drawing perpendicular bisectors.
RD Sharma Solutions for Class 6 Maths Chapter 18 offer step-by-step explanations of how to use each tool effectively. They include solved exercises, diagrams, and examples that help students learn correct usage, improving accuracy and confidence.
The geometrical tools covered include:
Ruler – to draw and measure straight lines
Compass – to draw arcs and circles
Protractor – to measure and construct angles
Divider – to compare lengths and mark distances
Set-squares – to draw right angles and parallel lines
Students can download RD Sharma Class 6 Chapter 18 PDF solutions from Infinity Learn. These PDFs are free and ideal for offline study and revision.