The Language of the Universe
Explore the infinite landscape of mathematics — from the elegance of pure theory to the power of applied computation.
Fields of Study
The study of symbols and rules for manipulating them. From linear equations to abstract rings and fields.
Limits, derivatives, and integrals. The mathematics of continuous change and accumulation.
Shapes, sizes, positions, and properties of figures in space — from Euclid to non-Euclidean worlds.
The queen of mathematics. Primes, divisibility, and the deep structure of the integers.
Making sense of data through probability distributions, inference, and the mathematics of uncertainty.
The study of properties preserved under continuous deformations. Coffee cups and donuts are the same.
Theorem of the Week — Euler's Identity
Euler's identity unites the five most fundamental constants in mathematics — e, i, π, 1, and 0 — in a single, breathtaking relationship. It bridges exponential growth, imaginary rotation, and the circle constant in perfect harmony.
For any real number θ, Euler's formula states that eiθ = cos(θ) + i·sin(θ). This can be derived from the Taylor series expansions of ex, cos(x), and sin(x) around 0.
Step 2 — Taylor SeriesRecall: ex = 1 + x + x²/2! + x³/3! + x⁴/4! + · · ·
cos(x) = 1 − x²/2! + x⁴/4! − · · ·
sin(x) = x − x³/3! + x⁵/5! − · · ·
Substitute x = iθ into the series for ex. Since i² = −1, i³ = −i, i⁴ = 1, the terms naturally split into the cosine and sine series: the even-powered terms (with alternating signs from i²ⁿ) form cos(θ), and the odd-powered terms form i·sin(θ).
Step 4 — Setting θ = πSetting θ = π: eiπ = cos(π) + i·sin(π) = −1 + i·0 = −1. Since eiπ = −1, we add 1 to both sides.
ConclusionTherefore: eiπ + 1 = 0. The five fundamental constants unite: the base of natural logarithms e, the imaginary unit i, the circle ratio π, the multiplicative identity 1, and the additive identity 0. ∎
Interactive
Scientific calculator with trig, logs, powers, and step-by-step evaluation.
Plot multiple functions, zoom & pan, trace values in real time.
Determinants, inverses, transpose, eigenvalues, and A×B multiplication.
Draw points, lines, circles, and polygons on an interactive canvas.
Daily Challenge
Number Theory
Prove that there are infinitely many prime numbers of the form 4k + 3, where k is a non-negative integer.
Hint: Consider a proof by contradiction similar to Euclid's classic argument for the infinitude of primes.
Solution
Mathematics is not about numbers, equations, computations, or algorithms — it is about understanding.
— William Paul Thurston, Fields Medalist