Cosine and sine rules
Mathematical Methods · Unit 4 — Further calculus, trigonometry and statistics · Trigonometry
Learning objectives (4)
LO-1Model and solve problems that involve the sine rule, cosine rule and the area formula in two - and three-dimensional contexts (including bearings, directions and angles of elevation and depression), with and without technology. Mathematical Methods 2025 v1.3LO-2Use the cosine rule, 𝑐2 = 𝑎2 + 𝑏2 − 2𝑎𝑏 cos(𝐶).LO-3Use the formula area = 1 2 𝑏 𝑐 sin (𝐴) to calculate the area of a triangle.LO-4Use the sine rule (ambiguous case is required), 𝑎 sin(𝐴) = 𝑏 sin(𝐵) = 𝑐 sin(𝐶), where 𝑎, 𝑏 and 𝑐 are the side lengths of the triangle and 𝐴, 𝐵 and 𝐶 are the corresponding opposite angles.
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