Edexcel A-Level Maths: Equations & formulae Questions And Answers.

Quadratic Formula - Answer x = -b±(√b²-4ac)/2a Straight Line Equation - Answer y-y₁ = m(x-x₁) Line Length Equation - Answer √(x₂-x₁)²+(y₂-y₁)² Sine Rule (Lengths) - Answer a/sinA = b/sinB = c/sinC Sine Rule (Angles) - Answer sinA/a = sinB/b = sinC/c Cosine Rule (Lengths) - Answer a² = b²+c²-2bc(cosA) Cosine Rule (Angles) - Answer cosA = (b²+c²-a²)/2bc Midpoint for lines - endpoints (x₁, y₁) & (x₂, y₂) - Answer (x₁+x₂)/2, (y₁+y₂)/2 Circle Equation - centre (a, b), radius (r) - Answer (x-a)²+(y-b)² = r² Circle Equation - centre (-f, -g), radius (√f²+g²-c) - Answer x²+y²+2fx+2gy+c = 0 Magnitude of a vector - Answer |a| = √x²+y² Tangent to a curve: y = f(x) - point w/co-ords (a, f(a)) - Answer y-f(a) = f'(a)(x-a) Normal to a curve: y = f(x) - point w/co-ords (a, f(a)) - Answer y-f(a) = -1/f'(a)(x-a) Multiplication Law of Logs - Answer logₐx+logₐy = logₐxy Division Law of Logs - Answer logₐx-logₐy = logₐ(x/y) Power Law of Logs - Answer logₐ(x^k) = klogₐx