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Cosine Rule - Side length Step one: To calculate amissing side c, you need 2sides and the includedangle. e.g. a, b & C. c2 = 42 + 2 – 2 x 4 x x cos o Step 2: Sub in the values for a, b and C. c2 = c2 = 42 + 72 – 2 x 4 x 7 x cos 138o Step 3: Enter into the calculator. Correct to 1 d.p., but leave all decimal places on your screen. Correct to 1 d.p. c2 = 106.6..... c = Step 3: Get the square root of your answer to get c by itself. cm c2 = 17.32 + 2 – 2 x 17.3 x x cos o Now, complete the steps without instructions c2 = 17.32 + 11.52 – 2 x 17.3 x 11.5 x cos 118o c2 = Correct to 1 d.p., but leave all decimal places on your screen. c2 = 618.3..... Correct to 1 d.p. c = m |