MathematicsClass 7Lines and Angles
Vertically Opposite Angles
Understanding that intersecting lines form equal pairs of vertically opposite angles.
Class 7 · MathematicsCBSE & ICSE SOF IMO
Definition
Vertically opposite angles are formed when two lines intersect each other at a single point. These opposite pairs of angles are always equal in measure to each other.
Key formula
Vertically Opposite Angles = Equal (e.g., Angle A = Angle C)
Worked examples
1
When two straight lines cross, if one angle is 50 degrees, the vertically opposite angle is also 50 degrees.
2
If the intersection forms an angle of 120 degrees, the angle directly across from it is 120 degrees.
3
In an 'X' shape where the top angle is 75 degrees, the bottom angle is also 75 degrees.
Common mistakes
- • Looking for angles that are physically 'vertical' or up-and-down instead of looking for opposite angles formed by intersecting lines.
- • Assuming vertically opposite angles are supplementary instead of equal.