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10.9 Chapter summary

  • An arc is part of the circumference of a circle.
  • To bisect means to divide into two equal parts.
  • A perpendicular bisector is a line that intersects another line at right angles and divides the line into two equal parts.
  • We measure angles in degrees (\(^{\circ}\)). We use a protractor to measure an angle.
  • When the sum of two angles is equal to \(90^{\circ}\), we say that the two angles are complementary angles.
  • When the sum of two angles is equal to \(180^{\circ}\), we say that the two angles are supplementary angles.
  • The longest side of a triangle lies opposite the biggest angle of the triangle.
  • The shortest side of a triangle lies opposite the smallest angle of the triangle.
  • The sum of the lengths of the two shorter sides of the triangle must be greater than the length of the longest side of the triangle.
  • A scalene triangle has three angles of different sizes.
  • An isosceles triangle has two equal sides. It therefore also has two equal angles.
  • An equilateral triangle has three equal sides and three equal angles. Each angle is equal to \(60^{\circ}\).
  • The sum of the interior angles of a triangle is \(180^{\circ}\).
  • The sum of the interior angles of a quadrilateral is \(360^{\circ}\).
  • A square is a quadrilateral with all sides equal in length and all interior angles equal to \(90^{\circ}\).
  • A rectangle is a quadrilateral with opposite sides equal in length and all interior angles equal to \(90^{\circ}\).
  • A parallelogram is a quadrilateral with opposite sides equal and parallel.
  • A rhombus is a quadrilateral with opposite sides parallel and all sides equal in length.