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