Here is a summary of the topic “Angles” from Class 6 Mathematics ICSE:

1. **Introduction to Angles**: Angles are formed when two rays originate from a common point. The common point is called the vertex.

2. **Types of Angles**:

– **Acute Angle**: An angle less than 90 degrees.

– **Right Angle**: An angle that is exactly 90 degrees.

– **Obtuse Angle**: An angle greater than 90 degrees but less than 180 degrees.

– **Straight Angle**: An angle that is exactly 180 degrees.

– **Reflex Angle**: An angle greater than 180 degrees but less than 360 degrees.

3. **Complementary and Supplementary Angles**:

– **Complementary Angles**: Two angles are complementary if their sum is 90 degrees.

– **Supplementary Angles**: Two angles are supplementary if their sum is 180 degrees.

**4. Adjacent Angles:** Angles that have a common arm and a common vertex, but no common interior points.

5. **Vertically Opposite Angles**: When two lines intersect, the angles opposite each other are called vertically opposite angles. They are equal in measure.

6. **Parallel Lines and Transversals**: When a transversal intersects two parallel lines, several pairs of angles are formed, such as corresponding angles, alternate interior angles, and alternate exterior angles.

7. **Properties of Angles**:

– The sum of angles around a point is 360 degrees.

– The sum of angles in a triangle is 180 degrees.

– The sum of angles in a quadrilateral is 360 degrees.

Understanding these concepts is essential for solving problems related to angles in mathematics.