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Topic 2: Trigonometry

Cosine and sine rules

10 hours

• Use 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. 1 interactive
• Use the cosine rule, 𝑐2 = 𝑎2 + 𝑏2 − 2𝑎𝑏cos(𝐶).
• Use the formula area = 1 2 𝑏 𝑐sin(𝐴) to calculate the area of a triangle.
• Model 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.