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AQA · 8365
Point–gradient form
The straight-line equation y−y1=m(x−x1)y-y_1=m(x-x_1)y−y1=m(x, using a known gradient and a known point on the line.
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Point of contact
The point where a tangent touches a circle.
Point of intersection
A point shared by two graphs. Its coordinates satisfy both equations.
Polygon
A closed plane shape made from straight sides.
Polynomial
An expression made from a finite sum of constant multiples of non-negative whole-number powers of a variable, such as 2x3−x+62x^3-x+62x3−x+6.
Positive angle
An angle measured by an anticlockwise rotation. In the unit-circle definitions, the rotation starts from the positive xxx-axis.
Power rule
The rule dydx=knxn−1\frac{dy}{dx}=knx^{n-1}dxdy=knxn−1 for differentiating y=kxny=kx^ny=kxn, where kkk is constant.
Prism
A three-dimensional solid with identical polygonal cross-sections throughout its length.
Product rule for counting
A counting method that multiplies the numbers of choices at successive stages, provided each earlier choice allows the stated number of choices at the next stage.
Pyramid
A solid with a polygonal base and triangular faces meeting at one point, called the apex.
Pythagoras' theorem
For a right-angled triangle with perpendicular sides of lengths aaa and bbb and hypotenuse of length ccc, a2+b2=c2a^2+b^2=c^2a2+b2=c2.
Pythagoras’ theorem
The relationship a2+b2=c2a^2+b^2=c^2a2+b2=c2 in a right-angled triangle, where ccc is the hypotenuse.
Pythagorean identity
The relationship sin2θ+cos2θ=1\sin^2\theta+\cos^2\theta=1sin2θ+cos2θ=1, connecting the squared sine and cosine of the same angle.
Pythagorean triple
A set of three positive integers aaa, bbb and ccc satisfying a2+b2=c2a^2+b^2=c^2a2+b2=c2. They can be the side lengths of a right-angled triangle.
Quadrant
One of the four regions into which the coordinate axes divide the plane, numbered I to IV anticlockwise from the top-right region.
Quadratic equation
An equation that can be written as ax2+bx+c=0ax^2+bx+c=0ax2+bx+c=0, where a≠0a\ne0a=0.
Quadratic expression
An algebraic expression whose highest power of the variable is 2, such as 2x2+6x+72x^2+6x+72x2+6x+7.
Quadratic inequality
An inequality in which the variable has highest power two, such as x2−9<0x^2-9<0x2−9<0.
Quadratic sequence
An ordered list of numbers whose nth term can be written as an2+bn+can^2+bn+can2+bn+c, where a≠0a\ne0a=0. Its second differences are constant and non-zero.
Quadrilateral
A polygon with four sides.
Radius
A line segment from the centre of a circle to its circumference, or the length of that segment.
Range
The set of possible output values of a function. Sine and cosine both have range −1≤y≤1-1\leq y\leq1−1≤y≤1.
Rate of change
How quickly yyy changes as xxx changes. At a particular point on a curve, this is measured by dydx\frac{dy}{dx}dxdy.
Ratio
A comparison of quantities. If AP:PB=m:nAP:PB=m:nAP:PB=m:n, the lengths APAPAP and PBPBPB contain mmm and nnn equal parts respectively.
Rational expression
A quotient of two polynomials, such as x2−4x+3\frac{x^2-4}{x+3}x+3x2−4, defined only where its denominator is non-zero.
Rationalising the denominator
Rewriting a fraction as an equivalent fraction with no surd in its denominator.
Rational number
A number that can be written as pq\frac{p}{q}qp, where ppp and qqq are integers and q≠0q\ne0q=0. Integers are also rational numbers.
Real number
A number on the number line, including integers, fractions and irrational numbers such as 2\sqrt{2}2 and π\piπ.
Reciprocal
The multiplicative inverse of a non-zero number or expression. The reciprocal of aaa is 1a\frac{1}{a}a1.
Reference angle
The acute angle between the final arm of an angle and the xxx-axis.
232 key terms