Solutions Library

78 curated probability theory problems with marking points and complete derivations.

52 stochastic process problems covering Poisson processes, Brownian motion, and core topics.

Quality-audited sequence and series problems from Zhejiang high-school exams with full derivations and rubrics.

54 curated permutation and combination problems covering core counting techniques, classic models, and complete worked solutions.

38 curated analytic geometry problems on conics — ellipse, hyperbola, parabola — with complete solutions and scoring rubrics.

30 curated triangle solving problems covering sine law, cosine law, and core problem-solving patterns with full derivations.

30 trigonometry problems covering identities, graph/property analysis, and triangle-solving patterns — with reference solutions and marking schemes.

40 curated solid geometry problems covering proofs, angles, distances, and comprehensive 3D reasoning with vector methods.