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3.1 Area

Mathematics · Grade 9 · 8 lessons in the design

What this covers

  • Area of a pentagon and a hexagon
  • Surface area of triangular and rectangular-based prisms
  • Surface area of triangular, rectangular and square-based pyramids, cones and spheres
  • Area of a sector and segment of a circle

What you will be able to do

  • calculate the area of a pentagon and a hexagon in different situations
  • work out the surface area of triangular and rectangular-based prisms
  • work out the surface area of triangular, rectangular and square-based pyramids
  • calculate the area of a sector and segment of a circle
  • work out the surface area of a cone in real-life situations
  • calculate the surface area of a sphere in real-life situations
  • recognise the use of area in real-life situations

Key questions

“How do we work out the area of different surfaces?”

Lessons

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  1. Area of a pentagon and a hexagon
    40 min · 1 practice tasks · quiz
    Split a regular polygon into identical triangles from its centre, then multiply one triangle by the number of sides.
  2. Nets: opening a solid out flat
    40 min · 1 practice tasks · quiz
    A net is the solid unfolded, and its total area is the surface area of the solid.
  3. Surface area of prisms
    40 min · 1 practice tasks · quiz
    A prism has two identical ends joined by rectangles; add both ends to all the rectangles.
  4. Surface area of pyramids
    40 min · 1 practice tasks · quiz
    A pyramid is one base plus triangles meeting at a point; the triangles use the slant height.
  5. Area of a sector
    40 min · 1 practice tasks · quiz
    A sector is a fraction of a circle, set by its angle at the centre out of 360 degrees.
  6. Area of a segment
    40 min · 1 practice tasks · quiz
    A segment is what is left when the triangle is taken off a sector.
  7. Surface area of a cone
    40 min · 1 practice tasks · quiz
    Opened flat, a cone is a sector; its curved surface area is pi r l, and a closed cone adds the base.
  8. Surface area of a sphere, and area at work
    40 min · 1 practice tasks · quiz
    A sphere has surface area 4 pi r squared; close the sub-strand by choosing the right method for real surfaces.