The document Chapter Notes - Lines and Angles Class 7 Notes | EduRev is a part of the Class 7 Course Mathematics (Maths) Class 7.

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**Angles**

-An angle is formed when lines or line segments meet.

-The lines that form an angle are called the sides or the arms of the angle.

-The common end point is called the** **vertex of the angle**.**

-The angle formed by two lines or line segments can be an acute angle**,** where the measure of the angle is less than 90Â°.

-The angle formed by two** **lines or line segments can be a right angle, where the measure of the angle is90Â°.

-The angle formed by two lines or line segments can be an obtuse angle, where the measure of the angle is greater than 90Â°.

-The angle formed by two lines or line segments can be a straight angle**,** where the measure of the angle is equal to 180Â°.

-The angle formed by two lines or line segments can be a reflex angle, where the measure of the angle is greater than 180Â°.

-When the sum of the measures of two angles is 90Â°, the angles are called complementary angles.

-When the sum of the measures of two angles is 180Â°**,** the angles are called** **supplementary angles.

-Adjacent angles have a** **common vertex and a common arm, and the non-common arms are on either side of the common arm.

-A linear pair is pair of adjacent angles whose non-common sides are opposite rays.

-Vertically opposite angles are opposite to each other and are equal.

**-Adjacent angles **have no common interior points.

-The angles in a** **linear pair are supplementary.

**-Angles **may have a common vertex and a common arm.

-Two angles are said to be adjacent angles if they have a **c****ommon side or arm.**

**-Two adjacent angle**s can be either** **supplementary or complementary.

**-If two adjacent angles are supplementary**, then they form a straight angle, and are also called a linear pair.

**-Two angles** that are not adjacent but have a common vertex are **called vertically opposite angles.**

-**Vertically opposite angles are equal**

**Pairs of Lines**

-Lines that meet at a point are called intersecting lines.

**-Lines that meet at a point are called intersecting line**s.

-Lines that always remain the same distance apart and never meet are called parallel lines.

**-A line **that intersects two or more lines at distinct points is **called a transversal.**

**-When two lines are intersected by a transversal,** pairs of corresponding angles, alternate angles and interior angles are formed.

-Angles formed on the same side of a transversal, on the same side of the two lines and at corresponding vertices are called **corresponding angles.**

-Angles formed on the opposite sides of the transversal at the two distinct points of intersection and between the two lines are **called alternate interior angles.**

-Angles formed on the opposite sides of the transversal at the two distinct points of intersection but outside the two lines are called **alternate exterior angles.**

-Angles that have different vertices, lie on the same side of the transversal and are interior angles are called **consecutive interior angles or allied or co-interior angles.**

-Each pair of interior angles on the same side of the transversal are supplementary, each pair of corresponding angles are equal and each pair of alternate interior angles are equal. -If a transversal cuts two lines such that the pairs of corresponding angles are equal, then the lines are parallel.

**-Eight angles** are formed when a transversal intersects two lines.

**-**The angles that lie between the lines are called** interior angles.**

-The angles that lie on the outer sides of the lines are called **exterior angles.**

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