Mathematical Formulas - Secondary 3

Concept sheet | Mathematics

Arithmetic and Algebra

The Properties of Operations

PropertyAdditionMultiplication
  1. Commutativity
||a+b=b+a||||a\times b=b\times a||
  1. Associativity
||(a+b)+c=a+(b+c)||||(a\times b)\times c=a\times(b\times c)||
  1. The neutral (identity) element
||a+0=0+a=a||||a\times1=1\times a=a||
  1. The absorbing (annihilating) element
 ||a\times0=0\times a=0||
  1. Opposite / Reciprocal
||a+-a=-a+a=0||||a\times\dfrac{1}{a}=1||
  1. The distributive nature of multiplication
||a\times(b\pm c)=a\times b\pm a\times c||

Real Functions

FunctionsBasic ruleTransformed rule
0 Degree||y=b|| 
1st degree||y=x||Functional formSymmetrical formGeneral form

||y=ax+b|||a|: rate of change (slope)

|b|: y-intercept||a=\dfrac{y_2-y_1}{x_2-x_1}||

||\dfrac{x}{a}+\dfrac{y}{b}=1|||a|: x-intercept

|b|: y-intercept

||Ax+By+C=0||
|\Rightarrow| Symmetrical||\begin{align}a_s&=\dfrac{-b_f}{a_f}\\b_s&=b_f\end{align}|||\Rightarrow| Functional||\begin{align}a_f&=\dfrac{-b_s}{a_s}\\b_f&=b_s\end{align}|||\Rightarrow| Functional||\begin{align}a_f&=\dfrac{-A}{B}\\b_f&=\dfrac{-C}{B}\end{align}||

|\Rightarrow| General

Find the common denominator and bring everything to the same side of the equation.

|\Rightarrow| General

Find the common denominator and bring everything to the same side of the equation.

|\Rightarrow| Symmetrical||\begin{align}a_s&=\dfrac{-C}{A}\\\\b_s&=\dfrac{-C}{B}\end{align}||

Geometry

Converting Units of Measure

​|\text{km}|​|\text{hm}|​|\text{dam}|​|\text{m}|​|\text{dm}||\text{cm}|​​|\text{mm}|
In this direction |\Rightarrow \times 10\qquad \qquad\qquad| In this direction |\Leftarrow \div 10|
​|\text{km}^2|​|\text{hm}^2|​|\text{dam}^2||\text{m}^2|​​|\text{dm}^2|​|\text{cm}^2|​|\text{mm}^2|
In this direction |\Rightarrow \times 100\qquad \qquad\qquad| In this direction |\Leftarrow \div 100|
​|\text{km}^3|​|\text{hm}^3|​|\text{dam}^3|​|\text{m}^3|​|\text{dm}^3|​|\text{cm}^3|​|\text{mm}^3|
In this direction |\Rightarrow \times 1000\qquad \qquad\qquad| In this direction |\Leftarrow \div 1000|

The Perimeter and Area of Plane Figures

FigurePerimeterArea
TriangleThe sum of all sides

|A =\dfrac{b\times h}{2}|

|A = \sqrt{p(p-a)(p-b)(p-c)}|
where
|p=\dfrac{a+b+c}{2}=| half-perimeter

|A=\dfrac{ab\sin C}{2}|
where |C=| measure of the angle located between sides |a| and |b|

Square|P=4 \times s||\begin{align} A &= s \times s\\
A &= s^2
\end{align}|
Rectangle|\begin{align} P &= b+h+b+h\\
P &= 2(b+h)
\end{align}|
|A=bh|
RhombusP=|4 \times s||A=\dfrac{D\times d}{2}|
ParallelogramThe sum of all sides|A=bh|
TrapezoidThe sum of all sides|A=\dfrac{(B+b)\times h}{2}|
Regular polygon|P=n \times s||A=\dfrac{san}{2}|
Any polygonThe sum of all sidesThe sum of the areas of all the triangles that make up the polygon
Circle|\begin{align} d &= 2r\\\\
r &= \frac{d}{2}
\end{align}|
||\begin{align} C &= \pi d\\\\
C &= 2 \pi r
\end{align}||
|A=\pi r^2|
Circular arc and sector of a circle|\displaystyle \frac{\text{Central angle}}{360^o}=\frac{\text{Arc length}}{2\pi r}||\displaystyle \frac{\text{Central angle}}{360^o}=\frac{\text{Area of sector}}{\pi r^2}|

The Area and Volume of Solids

​SolidsLateral areaTotal areaVolume
​Prism and cylinder

Sum of the areas of the lateral faces of the solid

|A_L=P_b\times h|

​Sum of the areas of all faces of the solid

|A_T = A_L+2A_b|

​|V=A_b\times h|
​Pyramid and cone

​Sum of the areas of the lateral faces of the solid

|A_L=\displaystyle \frac{P_b\times a}{2}|

Sum of the areas of all faces of the solid

|A_T = A_L+A_b|

​|V=\displaystyle \frac{A_b\times h}{3}|
​Sphere|A=4\pi r^2|​|V=\displaystyle \frac{4\pi r^3}{3}|

Measurements in Right Triangles

Theorems in a right triangle
  • Pythagorean theorem
    ​In any right triangle, the sum of the square of the legs |(a| and |b)| is equal to the square of the hypotenuse |(c).|||a^2+b^2 = c^2||

  • In any triangle, the measure of any one side is smaller than the sum of the measures of the other two sides.

  • In any isosceles triangle, the angles opposite the congruent sides are congruent.

  • In any right triangle, the acute angles are complementary |(90^\circ).|

  • Any right triangle with a |30^\circ| angle has a side opposite the |30^\circ| angle that is equal to half the hypotenuse.

Similar Figures and Solids

Similarity ratio (Scale factor)Area ratioVolume ratio
||k=\dfrac{\text{Length of image figure}}{\text{Length of initial figure}}||||k^2=\dfrac{\text{Area of image figure}}{\text{Area of initial figure}}||​||k^3=\dfrac{\text{Volume of image solid}}{\text{Volume of initial solid}}||

Analytic Geometry

Lines on a Cartesian Plane

ConceptFormulas
Displacements||\begin{align}\Delta x&=x_2-x_1\\[3pt]\Delta y&=y_2-y_1\end{align}||
Slope (rate of change) of a line||a=\dfrac{\Delta y}{\Delta x}=\dfrac{y_2-y_1}{x_2-x_1}||
Relative position of two lines with equations of the form |y=ax+b|Coinciding parallel linesDisjoint parallel linesPerpendicular lines
||\begin{align}a_1&=a_2\\[3pt]b_1&=b_2\end{align}||||\begin{align}​a_1&=a_2\\[3pt]b_1&\neq b_2\end{align}||||a_1=-\dfrac{1}{a_2}||

Probability and Statistics

The Probability of Events

ConceptFormulas
​Probability||\text{Probability}=\dfrac{\text{No. of favourable outcomes}}{\text{No. of possible outcomes}}||
​​Complementary probability||\mathbb{P}(A')=1-P(A)||
Probability of incompatible events||\mathbb{P}(A\cup B)=\mathbb{P}(A)+\mathbb{P}(B)||
​Probability of compatible events||\mathbb{P}(A\cup B)=\mathbb{P}(A)+\mathbb{P}(B)-\mathbb{P}(A\cap B)||

Measures of Central Tendency

​MeasureListed dataCondensed dataGrouped data
​​Mean||\overline{x}=\dfrac{\sum x_i}{n}||||\overline{x}=\dfrac{\sum x_i n_i}{n}||Approximate mean: ||\overline{x}=\dfrac{\sum m_i n_i}{n}||
​​Median

||\text{Rank}_\text{median}=\left(\dfrac{n+1}{2}\right)|| If |n| is odd, the median is obtained directly.

If |n| is even, the median is obtained by calculating the mean of the two central data values.

||\text{Rank}_\text{median}=\left(\dfrac{n+1}{2}\right)|| If |n| is odd, the median is obtained directly.

If |n| is even, the median is obtained by calculating the mean of the two central data values.

Medial class:

The class that contains the median.

The median of a grouped-data distribution is often estimated by calculating the middle of the medial class.

​ModeThe most frequent data valueThe most frequent data value

Modal class:

The class with the largest frequency

Measures of Dispersion

MeasureListed dataCondensed dataGrouped data
​Range||R=x_\text{max}-x_\text{min}||||R=\text{Value}_\text{Max}-\text{Value}_\text{Min}||

||R=\text{Boundary}_\text{upper}-\text{Boundary}_\text{lower}||

​Interquartile range||IR=Q_3-Q_1||||IR=Q_3-Q_1||||IR=Q_3-Q_1||
​Quarter range||Q=\dfrac{EI}{2}=\dfrac{Q_3-Q_1}{2}||||Q=\dfrac{EI}{2}=\dfrac{Q_3-Q_1}{2}||||Q=\dfrac{EI}{2}=\dfrac{Q_3-Q_1}{2}||