One page, the whole second course
Pick the topic from the dropdown and the form adapts: three sides for the SSS triangle solver, two angle fields for the law of sines, semicolon-separated rows for matrices, a single comma-separated field for vectors. Every member shows the substituted formula beneath the board, so each answer doubles as a worked example.
The formulas at a glance
Triangles: cos C = (a² + b² − c²)/(2ab), a/sin A = b/sin B, shoelace ½|x₁(y₂−y₃) + x₂(y₃−y₁) + x₃(y₁−y₂)|. Matrices: det = ad − bc, inverse = adjugate ÷ determinant. Vectors: u·w = |u||w|cos θ; u×w is perpendicular to both. Series: aₙ = a₁ + (n−1)d, Sₙ = n(a₁+aₙ)/2, and S = a₁/(1−r) only when |r| < 1. Numbers: two's complement = flip the bits and add one.
Worked example
- Solve a 3-4-5 triangle with the SSS member.
- Enter sides 3, 4, 5 — the inequality check passes.
- cos C = (9 + 16 − 25)/24 = 0, so C = 90° exactly.
- The board also lists A ≈ 36.87°, B ≈ 53.13°, area 6, and perimeter 12.
How to use it
- Choose the topic from the dropdown — triangles, matrices, vectors, sequences, number systems, complex numbers, or coordinates.
- Fill the fields; matrices and vectors go in as comma-separated numbers with rows split by semicolons.
- Read the result, the extra rows, and the substituted formula beneath the board.
- Copy, print, or share the link — it remembers the member and your values.