What the AMC 12 Tests
Everything on the AMC 10, plus: trigonometry (identities, sum/product formulas, law of sines/cosines, trig equations); logarithms and exponential equations; complex numbers (de Moivre, roots of unity, modulus geometry); polynomials in depth (Vieta for cubics/quartics, symmetric sums, roots of unity filter); conic sections; sequences and series including telescoping products and recursions with characteristic equations; combinatorics with generating-function intuition; probability with geometric probability and expected value; functions (composition, inverses, functional-equation style). Twenty-five questions, seventy-five minutes.
Gap Fillers
Ellipse with (foci), hyperbola with , parabola with focus . Reflective properties and the focus–directrix definition appear as "sum of distances" problems in disguise.
Probability favorable area total area. Two numbers in with : the complement is two right triangles of legs , so . Draw the region; the answer is usually a polygon or a circle piece.
Multiplication rotates and scales; is a distance; roots of form a regular -gon of circumradius (the roots of enclose area ). Sums of roots of unity vanish, which collapses many trig sums.