NCERT Class 6 Maths Chapter 2
Lines and Angles
This chapter introduces Class 6 CBSE students to fundamental concepts of geometry, including points, lines, line segments, rays, and the various types of angles. Students learn to identify, name, and measure angles, and explore angle pairs such as complementary, supplementary, and vertically opposite angles. The chapter builds the geometric foundation necessary for understanding shapes, proofs, and constructions in higher classes.
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Key Terms
- Line Segment
- A part of a line that has two definite endpoints and a fixed, measurable length.
- Ray
- A part of a line that has one fixed endpoint and extends infinitely in one direction.
- Angle
- The figure formed when two rays meet at a common point called the vertex, measured in degrees.
- Complementary Angles
- Two angles whose sum is 90°. Each is the complement of the other.
- Supplementary Angles
- Two angles whose sum is 180°. Each is the supplement of the other.
- Vertically Opposite Angles
- The pair of equal angles formed at the point of intersection of two straight lines; they are always equal.
Frequently Asked Questions
What is the difference between a line, line segment, and ray in Class 6 Maths?▾
A line extends infinitely in both directions with no endpoints. A line segment has two definite endpoints and a fixed length. A ray has one fixed endpoint and extends infinitely in one direction.
What are complementary and supplementary angles in Class 6?▾
Complementary angles are two angles whose sum is 90° (e.g., 30° and 60°). Supplementary angles are two angles whose sum is 180° (e.g., 110° and 70°). These are important angle relationships in geometry.
What are the types of angles in Class 6 Maths Chapter 2?▾
Types of angles include: acute angle (less than 90°), right angle (exactly 90°), obtuse angle (between 90° and 180°), straight angle (exactly 180°), reflex angle (between 180° and 360°), and complete angle (360°).
What are vertically opposite angles in Class 6?▾
When two straight lines intersect, they form two pairs of vertically opposite angles. These angles are always equal. For example, if one angle is 65°, the vertically opposite angle is also 65°.
How do you measure an angle using a protractor in Class 6 Maths?▾
Place the centre of the protractor at the vertex of the angle and align one arm with the 0° line. Read the degree where the other arm crosses the protractor scale. Make sure to read the correct scale (inner or outer) based on the angle's direction.
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