HOTmaths dictionary

This illustrated dictionary offers free access to over several hundred mathematical symbols, terms and definitions from the early secondary syllabus.

Select any letter to see examples of mathematical terms with clear explanations and helpful diagrams.

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© 2007 HOTmaths Pty Ltd

Term Definition halve divide by two

Related links: Decimals — Changing decimals to fractions Algebra — Words into algebra Length, perimeter and area — Areas of triangles Equations and inequalities — Keeping the balance Equations and inequalities — Equations to solve problems Circles and cylinders — Volume of a cylinder Analysing data — Analysing stem-and-leaf plots

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Term Definition HCF abbreviation for "highest common factor"

Related links: Number theory — Highest common factor (HCF) Number theory — HCF and LCM for large numbers Decimals — Changing decimals to fractions Ratios and rates — What is a ratio?

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Term Definition hectare (ha) unit of measurement of area equal to 10 000 m2

Related links: Length, perimeter and area — Areas of rectangles and squares Length, perimeter and area — Converting area units and estimating

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Term Definition height perpendicular distance from the base to the apex or top of a figure

Related links: Algebra — Substitution Length, perimeter and area — Areas of rectangles and squares Length, perimeter and area — Areas of triangles Length, perimeter and area — Converting area units and estimating Measuring solids — Volume of rectangular prisms 3D shapes — Drawing solids Pythagoras' theorem — Pythagoras, perimeter and area Representing data — Histograms and polygons Equations and inequalities — Equations and formulas Circles and cylinders — Volume of a cylinder Congruent and similar shapes — Scale drawings

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Term Definition height of triangle the perpendicular distance from the triangle"s base to its apex (the other vertex)

Related links: Algebra — Substitution Length, perimeter and area — Areas of triangles Measuring solids — Volume of any prism Pythagoras' theorem — Pythagoras, perimeter and area

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Term Definition heptagon a seven-sided polygon (with seven angles) Examples

Related links: 2D shapes — Plane shapes

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Term Definition hexagon a six-sided polygon (with six angles) Examples

Related links: Fractions — What is a fraction? Measuring solids — Volume of any prism 2D shapes — Plane shapes Ratios and rates — What is a ratio?

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Term Definition hexagonal numbers number pattern formed by adding successive layers of hexagons to one dot (first number, 1) (see also pentagonal numbers and figurate numbers)      1, 6, 12, 18 ...

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Term Definition hexahedron a solid with six faces A regular hexahedron, a cube (one of the five Platonic solids) has six congruent squares as faces.

Related links: 3D shapes — Classifying solids 3D shapes — Nets of solids

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Term Definition highest common factor (HCF) the largest number that is a factor of all the given numbers Example What is the highest common factor of 24 and 30? factors of 24: 1 × 24, 2 × 12, 3 × 8, 4 × 6 factors of 30: 1 × 30, 2 × 15, 3 × 10, 5 × 6 The common factors are 1, 2, 3 and 6. The highest common factor is 6.

Related links: Number theory — Highest common factor (HCF) Number theory — HCF and LCM for large numbers Decimals — Changing decimals to fractions Manipulating algebra — Factorising Ratios and rates — What is a ratio?

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Term Definition Hindu-Arabic numerals our current base-ten number system that uses the numerical symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Related links: Whole numbers — Ancient number systems Whole numbers — Roman and Greek numerals Whole numbers — Place value and expanded notation

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Term Definition histogram a special type of column graph for quantitative data with no gaps between the columns

Related links: Representing data — Histograms and polygons Representing data — Grouping data

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Term Definition horizontal flat or level; parallel to the horizon (also see vertical) Example The diagram shows a horizontal line.

Related links: Algebra — Patterns on the number grid Algebra — Patterns on the number grid Time — Time zones Representing data — Line, conversion and step graphs Representing data — Histograms and polygons The number plane — Plotting positive integers The number plane — Extending the number plane The number plane — Maps and plans

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Term Definition hypotenuse the longest side of a right-angled triangle (the side opposite the right angle)