Basic Angle Properties | Mathematics for GCSE/IGCSE - Year 11 PDF Download

What are the basic angle properties?

• Angles that meet at a point add up to 360°
• Angles that meet at a point on a straight line add up to 180°
• Vertically opposite angles are equal
  • Vertically opposite angles occur when two lines intersect. 
  • They are the angles on either side of the intersection that are opposite to each other.

What are the angle properties with triangles?

• The total of the three interior angles within any triangle equals 180°.
• In an isosceles triangle, two angles will have equal measures.
  • These equal angles correspond to those opposite the two sides of equal length.
• For an equilateral triangle, all three angles are equal in measure.
  • Each angle in an equilateral triangle measures 60°.

What are the angle properties with quadrilaterals?

• The total of the four interior angles in any quadrilateral amounts to 360 degrees.
• If the quadrilateral is a square or rectangle, all angles are equal, each at 90 degrees.
• Utilize symmetries within the quadrilateral to identify additional equal angles.
  • In a parallelogram or rhombus, opposite angles are equal.
  • Within a kite, one pair of opposite angles are equal.