// maths
∑ Maths
Algebra, trig, calculus, geometry.
Algebra
Algebra 5
Exponential calculator
y = a · b^x
Heron's formula via the Pythagorean theorem
d = (a²−b²+c²)/(2c), h = √(a²−d²), Area = ½·c·h = √(s(s−a)(s−b)(s−c))
Linear equation solver
ax + b = 0 → x = −b / a
Logarithm calculator
log_b(x) = ln(x) / ln(b)
Quadratic equation solver
x = (−b ± √(b²−4ac)) / 2a
Cube Identities 6
Cube of (a−b−c)
(a-b-c)³
Cube of a Difference (a−b)³
(a-b)³ = a³ - 3a² b + 3ab² - b³
Cube of a Sum (a+b)³
(a+b)³ = a³ + 3a² b + 3ab² + b³
Cube of a Trinomial (a+b+c)³
(a+b+c)³ = a³+b³+c³+3(a+b)(b+c)(c+a)
Difference (a+b)³ − (a−b)³
(a+b)³ - (a-b)³ = 6a² b + 2b³
Sum (a+b)³ + (a−b)³
(a+b)³ + (a-b)³ = 2a³ + 6ab²
Cube of Linear Binomial 1
Cube of a Linear Binomial (ax+b)³
(ax+b)³ = a³x³ + 3a²bx² + 3ab²x + b³
Difference of Two Squares 2
Difference of Two Squares a²−b²
a² - b² = (a-b)(a+b)
General Difference of Squares A²−B²
A² - B² = (A-B)(A+B)
Other Useful Identities 6
(a+b)² + (a−b)² = 2(a²+b²)
(a+b)² + (a-b)² = 2(a² + b²)
(a+b)² − (a−b)² = 4ab
(a+b)² - (a-b)² = 4ab
(ax+b)(cx+d)
(ax+b)(cx+d) = acx² + (ad+bc)x + bd
(x+a)(x+b)
(x+a)(x+b) = x² + (a+b)x + ab
(x+a)(x−a)
(x+a)(x-a) = x² - a²
(x−a)(x−b)
(x-a)(x-b) = x² - (a+b)x + ab
Product of Three Terms 1
a³+b³+c³−3abc
a³+b³+c³-3abc = (a+b+c)(a²+b²+c²-ab-bc-ca)
Square Identities 6
Square of (a+b−c)
(a+b-c)² = a²+b²+c²+2ab-2bc-2ca
Square of (a−b+c)
(a-b+c)² = a²+b²+c²-2ab-2bc+2ca
Square of (a−b−c)
(a-b-c)² = a²+b²+c²-2ab-2ca+2bc
Square of a Difference (a−b)²
(a-b)² = a² - 2ab + b²
Square of a Sum (a+b)²
(a+b)² = a² + 2ab + b²
Square of a Trinomial (a+b+c)²
(a+b+c)² = a²+b²+c²+2ab+2bc+2ca
Square of Linear Trinomial 1
Square of a Linear Trinomial (ax+by+c)²
(ax+by+c)² = a²x² + b²y² + c² + 2abxy + 2bcy + 2cax
Substitution Identities 4
If x + 1/x = a, then x² + 1/x² = a² − 2
x + 1/x = a => x² + 1/x² = a² - 2
If x + 1/x = a, then x³ + 1/x³ = a³ − 3a
x + 1/x = a => x³ + 1/x³ = a³ - 3a
If x − 1/x = a, then x² + 1/x² = a² + 2
x - 1/x = a => x² + 1/x² = a² + 2
If x − 1/x = a, then x³ − 1/x³ = a³ + 3a
x - 1/x = a => x³ - 1/x³ = a³ + 3a
Sum / Difference of Two Cubes 2
Difference of Two Cubes a³−b³
a³ - b³ = (a-b)(a² + ab + b²)
Sum of Two Cubes a³+b³
a³ + b³ = (a+b)(a² - ab + b²)
Arithmetic
Arithmetic 5
Fraction calculator
a/b op c/d → simplest form
GCD (Greatest Common Divisor) calculator
gcd via Euclid's algorithm
LCM (Least Common Multiple) calculator
lcm(a,b) = |a·b| / gcd(a,b)
Percentage calculator
part = (p/100)·whole ; p = (part/whole)·100
Ratio calculator
a:b ÷ gcd(a,b) = simplest ratio
Geometry
2D Shapes 9
Circle Area Calculator
area = πr² ; circumference = 2πr ; diameter = 2r
Ellipse Area Calculator
area = πab ; circumference ≈ π[3(a+b) − √((3a+b)(a+3b))] (Ramanujan)
Parallelogram Area Calculator
area = base×height ; perimeter = 2(base+side)
Rectangle Area Calculator
area = length×width ; perimeter = 2(length+width) ; diagonal = √(l²+w²)
Regular Polygon Calculator
area = ¼·n·s²·cot(π/n) ; interior angle = (n−2)×180/n
Rhombus Area Calculator
area = ½×d₁×d₂ ; side = ½√(d₁²+d₂²) ; perimeter = 4×side
Square Area Calculator
area = side² ; perimeter = 4×side ; diagonal = side×√2
Trapezoid Area Calculator
area = ½(a+b)×h ; perimeter = a+b+c+d
Triangle Area Calculator
½×base×height, or Heron: √(s(s−a)(s−b)(s−c)) with s = (a+b+c)/2
3D Solids 7
Cone Volume Calculator
volume = ⅓πr²h ; slant = √(r²+h²) ; surface = πr(r+slant)
Cube Volume Calculator
volume = s³ ; surface area = 6s² ; space diagonal = s√3
Cuboid Volume Calculator
volume = l×w×h ; surface area = 2(lw+lh+wh) ; diagonal = √(l²+w²+h²)
Cylinder Volume Calculator
volume = πr²h ; lateral = 2πrh ; total = 2πr(r+h)
Sphere Volume Calculator
volume = 4/3·πr³ ; surface area = 4πr²
Square Pyramid Volume Calculator
volume = ⅓a²h ; slant = √(h²+(a/2)²) ; surface = a² + 2a·slant
Torus Volume Calculator
volume = 2π² R r² ; surface area = 4π² R r
Angles 1
Angles & angle types
acute < 90° · right = 90° · obtuse 90–180° · straight = 180° · reflex 180–360°
Triangles 2
Heron's formula
Area = √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2
Pythagoras' theorem
a² + b² = c²
Real-World Trigonometry
Acoustics & Music 1
Sound Beat Frequency
f_beat = |f₁ − f₂|; sin(2πf₁t) + sin(2πf₂t)
Astronomy 1
Distance to a star by parallax
distance (pc) = 1 / parallax (arcsec)
Construction 1
Roof pitch and rafter length
pitch = tan⁻¹(rise / run), rafter = √(rise² + run²)
Electronics 1
AC Circuit Voltage
v(t) = V·sin(2πft + φ)
Engineering & Rides 1
Ferris Wheel Height
h(t) = R·sin(2πt/T − π/2) + R + clearance
Forensics 1
Impact angle of a trajectory
impact angle = tan⁻¹(vertical drop / horizontal travel)
Graphics & Technology 1
2D Rotation (Graphics)
x′ = x·cosθ − y·sinθ; y′ = x·sinθ + y·cosθ
Heights & Distances 1
Measuring a tree's height
height = distance × tan θ + eye height
Marine Biology 1
Ocean depth from angled sonar
depth = slant range × sin θ
Navigation & Aviation 1
Tracking an aircraft's altitude
altitude = ground distance × tan θ
Oceanography 1
Tide Height Prediction
h(t) = A·sin(2πt/T) + mean
Physics & Motion 1
Pendulum Period & Swing
T = 2π√(L/g); θ(t) = θ₀·cos(2πt/T)
Trigonometry
Advanced Applications 8
Euler's Formula & de Moivre
e^{iθ} = cos θ + i sin θ; (r(cosθ+isinθ))ⁿ = rⁿ(cos nθ + i sin nθ)
Inverse Trigonometric Functions
arcsin x ∈ [−90°,90°]; arccos x ∈ [0°,180°]; arctan x ∈ (−90°,90°)
Modelling Periodic Phenomena
y = A sin(B(x − C)) + D — amplitude |A|, period 360°/B, midline D
Polar Coordinates
x = r cos θ, y = r sin θ; r = √(x²+y²), θ = atan2(y, x)
Real-World Trig Problems
elevation: h = d·tanθ; ladder: h = L·sinθ; wheel: y = D + R·sin(ωt)
Reciprocal Trig Functions
sec θ = 1/cos θ; cosec θ = 1/sin θ; cot θ = cos θ/sin θ
Small-Angle Approximation
sin x ≈ x, tan x ≈ x, cos x ≈ 1 − x²/2 (x in radians)
Wave Superposition (a sinx + b cosx)
a sin x + b cos x = R sin(x + α), R = √(a²+b²), α = arctan(b/a)
Foundations 2
Intro to sin, cos, tan
sin = O/H · cos = A/H · tan = O/A (SOH-CAH-TOA)
Similar triangles & ratios
a₁ / a₂ = b₁ / b₂ (corresponding sides are in proportion)
Non-Right-Angle Trigonometry 5
Ambiguous case (SSA)
sin B = b·sin A / a → B or 180°−B may both be valid
Area of any triangle (½·a·b·sin C)
Area = ½·a·b·sin C (a, b sides; C the angle between them)
Cosine rule
c² = a² + b² − 2ab·cos C
Heron's formula via the cosine rule
Area = ½·a·b·sin C, with cos C = (a²+b²−c²)/(2ab) → Heron's √(s(s−a)(s−b)(s−c))
Sine rule
a / sin A = b / sin B = c / sin C
Right-Angle Trigonometry 5
3D trigonometry
diagonal = √(l² + w² + h²) · angle = tan⁻¹(h / √(l²+w²))
Angles of elevation & depression
tan θ = height / distance
Compass bearings
bearing = (90° − atan2(N, E)) mod 360°
Find a side
opp = hyp·sinθ · adj = hyp·cosθ · opp = adj·tanθ
Find an angle
θ = sin⁻¹(O/H) · cos⁻¹(A/H) · tan⁻¹(O/A)
Trigonometric Equations 2
General Solution
sin: x=α+360°n or 180°−α+360°n; cos: x=±α+360°n; tan: x=α+180°n
Solving Trig Equations
sin x = k → x = sin⁻¹k and its symmetric partners, within the domain
Trigonometric Functions & Graphs 7
Degrees & radians
radians = degrees × π/180 · degrees = radians × 180/π
Period & amplitude
amplitude = |A| · period = 360°/|B| = 2π/|B|
The unit circle
P = (cos θ, sin θ) on the circle of radius 1
Transformations: y = A·sin(Bx + C) + D
y = A·sin(Bx + C) + D
y = cos x
y = cos x (amplitude 1, period 360° = 2π)
y = sin x
y = sin x (amplitude 1, period 360° = 2π)
y = tan x
y = tan x = sin x / cos x (period 180°, asymptotes where cos x = 0)
Trigonometric Identities 6
Compound-Angle Formulae
sin(A±B)=sinA cosB ± cosA sinB; cos(A±B)=cosA cosB ∓ sinA sinB
Double-Angle Formulae
sin2A=2sinAcosA; cos2A=cos²A−sin²A=2cos²A−1=1−2sin²A; tan2A=2tanA/(1−tan²A)
Exact Trigonometric Values
sin 30°=1/2, cos 30°=√3/2, sin 45°=cos 45°=√2/2, sin 60°=√3/2
Half-Angle Formulae
sin(A/2)=±√((1−cosA)/2); cos(A/2)=±√((1+cosA)/2); tan(A/2)=(1−cosA)/sinA
Product-to-Sum Formulae
2sinAcosB=sin(A+B)+sin(A−B); 2cosAcosB=cos(A−B)+cos(A+B)
Pythagorean Identities
sin²θ + cos²θ = 1
3D Models of Numbers
Chaos & Dynamics 1
Lorenz Attractor
the butterfly effect in 3D
Famous Equations 2
Euler's Formula
e^(iθ) = cos θ + i sin θ
Fourier Series
building a square wave from sine waves
Sequences & Patterns 4
Collatz Trajectories
the 3n+1 hailstone paths
Divisor Surface
height = number of divisors d(n)
Factorial Spiral
n! as a log-height spiral
Prime Spiral
primes on a golden-angle spiral
Surfaces & Shapes 2
Morphing Surface
z = f(x, y) animated over time
Pascal Terrain
binomial coefficients as a 3D terrain
Probability 3
Combination Calculator
nCr = n! / (r! (n − r)!)
Permutation Calculator
nPr = n! / (n − r)!
Probability Calculator
P = favourable outcomes / total outcomes
Statistics 5
Average (Mean) Calculator
mean = (sum of values) / (count of values)
Median Calculator
median = middle value of the sorted list
Mode Calculator
mode = the value(s) that appear most often
Standard Deviation Calculator
σ = √(Σ(x − mean)² / N) ; sample s divides by N − 1
Variance Calculator
population σ² = Σ(x − mean)² / N ; sample s² divides by N − 1