Edexcel Mathematics Higher Tier, November 2009 (1380/4H) (Paper 4, calculator)


Question 26 a) area of triangle is given in formulae sheet. It is 


to the angle c area = 


 ab sin c where a and b are the sides that are next  x 5 x 8 x sin 75⁰ = 19.3 cm2 (correct to 3 significant figures)


b) this time we need to use the cosine rule (again given in formulae sheet) a2 = b2 + c2 – 2bccosA


a is the side we are trying to find let b = 5, c = 8 and A is 75⁰


a2 = 52 + 82 – (2 x 5 x 8 x cos 75⁰) a2 = 25 + 64 – (80 x cos 75⁰) a2 = 89 – 20.7055… = 68.2944… square root both sides a = √68.2944.. = 8.26 cm(to 3 significant figures)


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