What is Mathematics?: An Elementary Approach to Ideas and Methods

a₁ algebraic altitude triangle angle calculus circle closed curve complex numbers concept conic consider construction continuous function coördinates corresponding cross-ratio decimal defined definition denote derivative differential digits distance domain doubling the cube elements ellipse equal equation Euler's formula example Exercise expression fact Figure finite number follows formula function f(x given Hence hyperbola infinite integers intersection interval intuitive inverse inverse function irrational numbers Jordan curve theorem Leibniz length limit mathematical mathematical induction minimum multiplication nested intervals obtain P₁ parallel plane polygon positive integer positive number primes problem projective geometry proof prove quadratic residue radius rational numbers real numbers root segment sequence side simple solution Steiner's problem straight line surface symbol tangent tends to infinity theorem tion topological transformation variable vertices x-axis x₁ zero