Angle Rules

Angle Rules

Rules for Angles on a Straight Line

  • Angles that are situated on a straight line always add up to 180 degrees. This is known as the straight line rule.

Rules for Angles at a Point

  • A full revolution, or the total angles around a point, equate to 360 degrees. The angles surrounding a point always total this value.

Rules for Vertically Opposite Angles

  • When two lines intercept each other, they create pairs of vertically opposite angles. These vertically opposite angles are always equal.

Rules for Angles in a Triangle

  • The sum of all the angles within a triangle always adds up to 180 degrees. This is known as the triangle angle sum property.

Rules for Angles in a Quadrilateral

  • The sum of all the angles in any quadrilateral equals 360 degrees. This rule remains the same regardless of the shape of the quadrilateral.

Rules for Corresponding Angles

  • When two straight, parallel lines are crossed by a third line (transversal), the angles that are situated in the same relative position at each intersection are called corresponding angles. These angles are always equal.

Rules for Alternate Angles

  • Still following the scenario of two straight, parallel lines crossed by a third, another kind of equal angles are formed. These are called alternate angles (or “Z” angles) and are positioned on opposite sides of the transversal but inside the parallel lines.

Rules for Interior Angles

  • Also resulting from two parallel lines crossed by a transversal, interior angles (or “C” angles) are found on the same side of the transversal but inside the parallel lines. Pairs of interior angles always add to 180 degrees.

Rules for Angles in Regular Polygons

  • To find the sum of the interior angles in a polygon, use the formula (n-2) x 180, where n is the number of sides in the polygon.
  • In a regular polygon (one where all sides and angles are equal), each individual angle can be found with the formula [(n-2) x 180] / n.

Remember, a clear understanding of the standard angle rules is crucial for solving problems in geometry. Always think about which rules may apply to a given problem and check your calculations carefully.