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The circumference (C) is another term for the perimeter of a circle.
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The diameter (D) of a circle is the name given to the straight-line distance across a circle through its centre.
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The straight-line distance from the centre of the circle to the circumferences is called the radius (r).
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The circumference of a circle is given by the formula C = πD
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The diameter is double the radius, so the other way to write the formula for the circumference is C = 2πr.
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The perimeter of a shape is the total distance around the shape. To find the perimeter of a shape:
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-identify the length of each side
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-ensure that all measurements are in the same units
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-add all side lengths together and include units with your answer.
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Metric units of length include millimetres (mm), centimetres (cm), metres (m) and kilometres (km).
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10 mm is 1 cm. 100 cm is 1 m. 1000 m is 1 km.
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Time is one of our most important systems of measurement.
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The suffixes am and pm are used to indicate morning and afternoon.
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Volume is the amount of space inside a three-dimensional object. Volume is measured in cubic units such as mm3, cm3 or m3.
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Prisms are solid shapes with identical opposite polygonal ends which are joined by straight edges. They can be cut into identical slices, called cross sections.
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Prisms are named after the shape of their cross-section. Objects such as spheres, cones and square pyramids are not prisms.
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The volume of any prism is given by the formula V = A x H.
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The volume of a rectangular prism is V = lwh.
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The volume of a cube is V = l3.
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The area of a shape is the amount of flat surface enclosed by the shape.
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Area is measured in square units:
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100 sq mm is 1 sq cm. 10000 sq cm is 1 sq m. 1000000 sq m is 1 sq km.
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Large areas of land can be measured in hectares (ha). 1 ha = 10000 m2.
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The area of a rectangle is A = l x w.
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The area of a square is l2.
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The area of a triangle is ½ x b x h.
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The area of a parallelogram is b x h.
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The area of a rhombus is d1 x d2 ÷ 2.
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The area of a kite is d1 x d2 ÷ 2.
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The area of a circle is πr2.
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The area of a trapezium is ½ (a + b) x h.
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Time changes as we travel around the world. If we travel east, we need to set our watches ahead. If we travel west, we need to set our watches back.
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Many countries around the world have daylight-saving time during summer so that people can make the most of warm weather. When daylight-saving time begins, clocks are turned forward by 1 hour at 2:00 am.
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At the end of daylight-saving time, the clocks are then turned back by 1 hour at 3:00 am.
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
