Revision Note - Math

Exterior Angle of Triangle

Result: $a+b=c$

Reference: ext. $\angle$ of $\Delta$… Read

Math

Factor Theorem

If $f(x)$ is divisible by $(x-a)$, where $a$ is a real number

Math

Factorial

For $n$ different objects, if we have a queue of all $n$ objec… Read

Data Handling

Fibonacci Sequence

The sequence of numbers $1$, $1$, $2$, $3$, $5$, $8$, $13$, $… Read

Math

Geometric Sequences

Let $T(1)$, $T(2)$, …, $T(n)$ be an geometric sequen… Read

Math

Growth and Decay

Denote $O$ and $N$ the old value and new value respectively, … Read

Math

Identities of Cubes

For any real numbers $a$ and $b$.

Sum of cubes
$a^3+b^3 \equi

Identities

Identities of Squares

For any real numbers $a$ and $b$.

Difference of squares
$a^2

Identities

Index of Earthquakes – the Richter Scale

The relation between the magnitude ($M$) of an earthquake a… Read

Exponential and Logarithm

Inter-quartile Range

Let $Q_3$ and $Q_1$ be the upper and lower quartile respecti… Read

Data Handling

Intercept Theorem

Condition: $AB=BC$ and $AD//BE//CF$

Result: $DE=EF$

Refe… Read

Math

Interests

Simple interest
Denote $P$ the principal, $r\%$ the intere

Math

Interior Angle and Exterior of Polygon

Angle sum of polygon
Angle sum of $n$-gon $=(n-2)\times180

Math

Inverse Variation

If $y \propto \frac{1}{x}$ (i.e. $y$ varies inversely as $x… Read

Math

Joint Variation

If $y$ varies directly as $x$ and inversely as $z$, then we ha… Read

Math

Kites

Definition: A quadrilateral with two pairs of equal sides.

Math

Laws of Indices

For any real numbers $a$, $b$ and $c$, any rational numbers $… Read

Exponential and Logarithm

Laws of Logarithm

For any positive real numbers $a$, $b$ and $c$, any rational … Read

Exponential and Logarithm

Measurement of Sound

The relation between the loudness ($D$ dB) of a sound and the … Read

Exponential and Logarithm

Mid-point Formula

For two points $A(x_1,y_1)$ and $B(x_2,y_2)$, the coordin… Read

Coordinates