Maths (school) glossary
67 key terms from Maths (school), A to Z. Each is explained in one plain sentence and links to its free lesson.
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A
- Adding fractionsNumber and ratio
- To add fractions, first make the bottom numbers (denominators) the same, then add the top numbers (numerators).
- Angle rulesAngles and area
- Angles on a straight line add up to 180 degrees, angles around a point add up to 360 degrees, and angles in a triangle add up to 180 degrees.
- Angles in parallel linesAngles and area
- When a line crosses two parallel lines, matching angles are equal.
- Angles in polygonsAngles and area
- The interior angles of a polygon with n sides add up to (n - 2) x 180 degrees.
- Angles of elevation and depressionPythagoras and trigonometry
- The angle of elevation is measured upwards from the horizontal.
- Arcs and sectorsAngles and area
- A sector is a slice of a circle, like a pizza wedge.
- Area of 2D shapesAngles and area
- The amount of flat space inside a shape, measured in square units.
- AveragesProbability and statistics
- Single numbers that sum up a set of data.
B
C
- Changing the subjectEquations and formulae
- Rearranging a formula so a different letter stands on its own on one side.
- Circle theoremsAngles and area
- Rules about angles inside circles.
- CirclesAngles and area
- The circumference is the distance around a circle and the area is the space inside.
- Congruent shapesShape and space
- Shapes that are exactly the same size and shape.
- ConstructionsShape and space
- Accurate drawings made with a pair of compasses and a ruler, without measuring angles.
- CoordinatesGraphs
- A pair of numbers (x, y) that gives the exact position of a point on a grid.
- Cosine rulePythagoras and trigonometry
- For any triangle, c^2 = a^2 + b^2 - 2ab cos C.
- Cubic and reciprocal graphsGraphs
- A cubic graph, such as y = x^3, is an S-shape.
D
- Difference of two squaresAlgebra basics
- A special pattern: a squared number minus another squared number factorises into (a - b)(a + b).
- Direct proportionNumber and ratio
- Two amounts are in direct proportion when doubling one also doubles the other.
- Distance between two pointsPythagoras and trigonometry
- You can use Pythagoras on a coordinate grid.
- Distance-time graphsGraphs
- A graph with time across and distance up.
- Double bracketsAlgebra basics
- Multiplying two brackets by making sure every term in the first bracket meets every term in the second.
E
- EnlargementShape and space
- Making a shape bigger or smaller by a scale factor, from a fixed point called the centre of enlargement.
- Exact trigonometry valuesPythagoras and trigonometry
- Some angles have neat values you can write without a calculator: sin 30 = 1/2, cos 60 = 1/2, tan 45 = 1.
- Expanding bracketsAlgebra basics
- Multiplying everything inside the brackets by the number or letter outside.
F
- FactorisingAlgebra basics
- The reverse of expanding: pulling out the biggest common factor and putting the rest in brackets.
- Factorising quadraticsAlgebra basics
- Writing an expression like x^2 + 7x + 12 as two brackets multiplied together.
- Finding a missing anglePythagoras and trigonometry
- Use the inverse button (sin^-1, cos^-1 or tan^-1) on your calculator to turn a ratio back into an angle.
- Finding a missing sidePythagoras and trigonometry
- Put the angle and known side into the correct ratio, then rearrange to get the unknown side.
- Forming equationsEquations and formulae
- Turning a worded problem into an equation by letting a letter stand for the unknown.
G
- GradientGraphs
- How steep a line is.
H
- HCF and LCMNumber and ratio
- The highest common factor (HCF) is the biggest number that divides into both numbers.
I
- Independent eventsProbability and statistics
- Events where one result has no effect on the other.
- InequalitiesEquations and formulae
- Statements using <, >, or the signs for 'less than or equal' and 'more than or equal' that show a range of possible values.
L
- Laws of indicesNumber and ratio
- Rules for combining powers.
M
- Mean from a frequency tableProbability and statistics
- When data is in a table, multiply each value by its frequency, add these up, then divide by the total frequency.
- Midpoint of a lineGraphs
- The point exactly halfway along a line segment.
- Mutually exclusive eventsProbability and statistics
- Events that cannot happen at the same time.
N
- nth term of a sequenceAlgebra basics
- A rule that gives any term in a number pattern from its position n.
P
- Parallel and perpendicular linesGraphs
- Parallel lines never meet and have the same gradient.
- Percentage changeNumber and ratio
- A way to show how much something went up or down compared with where it started.
- Percentage of an amountNumber and ratio
- A percentage means 'out of 100'.
- Probability scaleProbability and statistics
- A number from 0 to 1 showing how likely something is.
- Pythagoras' theoremPythagoras and trigonometry
- In a right-angled triangle, the square of the longest side (the hypotenuse) equals the sum of the squares of the other two sides: a^2 + b^2 = c^2.
Q
- Quadratic graphsGraphs
- The graph of an equation with x^2 in it is a smooth U-shaped curve called a parabola.
R
- RatioNumber and ratio
- A way to compare amounts.
- ReflectionShape and space
- Flipping a shape over a mirror line so each point lands the same distance on the other side.
- Relative frequencyProbability and statistics
- An estimate of probability from an experiment: the number of times something happened divided by the total number of trials.
- RotationShape and space
- Turning a shape around a fixed point, called the centre of rotation, by a certain angle and direction.
S
- Scatter graphs and correlationProbability and statistics
- A scatter graph plots pairs of data as points.
- Similar shapesShape and space
- Shapes with the same angles but different sizes.
- Simplifying expressionsAlgebra basics
- Tidying an expression by adding or subtracting 'like terms', which are terms with exactly the same letter part.
- Simultaneous equationsEquations and formulae
- Two equations with two unknowns that are both true at once.
- Sine rulePythagoras and trigonometry
- For any triangle, side a over sin A equals side b over sin B.
- Sine, cosine and tangentPythagoras and trigonometry
- Three ratios linking an angle in a right-angled triangle to its sides: sin = opposite / hypotenuse, cos = adjacent / hypotenuse, tan = opposite / adjacent.
- Solving linear equationsEquations and formulae
- Finding the value of the unknown letter by doing the same thing to both sides until the letter is alone.
- Solving quadratics by factorisingEquations and formulae
- Writing the quadratic as two brackets equal to zero, then setting each bracket to zero to find the solutions.
- Standard formNumber and ratio
- A short way to write very big or very small numbers as a number between 1 and 10 times a power of 10.
- SubstitutionAlgebra basics
- Replacing each letter in an expression with a number, then working out the answer.
T
- The quadratic formulaEquations and formulae
- A formula that solves any quadratic ax^2 + bx + c = 0, even when it does not factorise easily.
- TranslationShape and space
- Sliding a shape without turning or flipping it.
- Tree diagramsProbability and statistics
- A branching picture showing all possible outcomes of events in order.
U
- Unknowns on both sidesEquations and formulae
- When the letter appears on both sides, first move the letter terms to one side, then solve as normal.
V
- VectorsShape and space
- A vector has both a size and a direction.
- Volume of prisms and cylindersAngles and area
- A prism has the same shape all the way through.
Y
- y = mx + cGraphs
- The equation of a straight line.