GCSE Maths (Edexcel)

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Geometry and measures Mensuration and calculation

Area of a Circle

4:20 know the formulae: circumference of a circle = 2πr = πd, area of a circle = πr²; calculate: perimeters of 2D shapes, including circles; areas of circles and composite shapes; surface area and volume of spheres, pyramids, cones and composite solids
Spec G17
Previous Areas of Compound Shapes Next Area of a Sector
  • The area of a circle is proportional to the radius squared
  • The formula for the area of a circle is pi times the radius squared
  • Pi is the ratio between the circumference and diameter of a circle
  • The formula can be shown to be correct by splitting a circle into sectors and constructing a rectangle from them
  • As the number of sectors increases, the shape becomes closer to a true rectangle
  • The area of the rectangle is equal to the area of the circle
  • The area of a circle can be calculated using the formula pi times the radius squared
  • Example: Calculate the area of a circle with a radius of 15 cm using the formula pi times the radius squared

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372

questions for Geometry and measures

190

questions for Mensuration and calculation