In this post, you will learn lines and angles class9 NCERT solutions. In NCERT solutions for class 9 maths lines and angles, you will learn the properties of the angles formed when two lines intersect each other. You can also go through activity 1.10class 9 science.

**NCERT Class 9 Maths Lines and Angles**

In ncert class 9 maths lines and angles, you will also
study the properties of the angles formed when a line intersects two or more
parallel lines at distinct points.

**Basic Terms and Definitions Class 9 Maths Chapter 6**

** 1. ****Ray
– **A
part of a line with one endpoint is called a ray.

** 2. ****Line
-segment- A** part of a line with two endpoints is
called a line segment.

** 3. ****Collinear
points- **When three or more points lie on the same line, they are
called collinear points.

** 4. ****non-collinear
points- **When three or more points do not lie on the same line, they are called non-collinear points.

** 5. ****Angle
– **When
two rays originate from the same endpoint, an angle is formed between them.

** 6. ****Arms
– **The
rays making an angle are called the arms.

** 7. ****Vertex
– **the
origin point of both arms of an angle is known as the vertex.

** 8. ****Acute
angle **– The angle which measures between 0° and 90°.

** 9. ****Right
angle -**This angle is equal to 90°.

** 10. ****Obtuse angle- **The angle that is greater than 90° but less than 180° is called the obtuse angle.

** 11. ****Straight angle -**The
angle that is equal to 180° is called a straight angle.

**12**. **Reflex angle -** The
angle that is greater than 180° but less than 360° is called a reflex angle.

** 13. ****Complementary angle – **Two angles whose sum is 90°

are called complementary angles.

** 14. ****Supplementary angles –** Two
angles whose sum is 180° are called supplementary
angles.

** 15. ****Adjacent angles – **When
two angles have a common vertex and their common arms and their non-common
arms on different sides of the common arms are called adjacent angles.

** 16.
****Linear
pairs of angles** – When a ray originating from a line (like OC
)

Here angle formed by this ray (like x and y) will be linear pair of angles. The sum of these angles is always 180° (x+y=180)

17. **Vertically opposite angles – **when two lines intersect each other then angles
formed on the opposite sides will be equal and are known as vertically

opposite angles

so, these are some basic terms and definitions of lines and
angles class9 ncert solutions. In NCERT solutions. To better understand the
basic terms and definitions of NCERT Class 9 Maths Lines and Angles, you can
watch the video given below.

**Watch the video to understand the topic more
efficiently.**