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(Cosine Formulae) if `a ,b ,c` are the lengths of the sides opposite respectively to the angles `A ,B ,C` of a triangle `A B C ,` show that `cosA(b^2+c^2-a^2)/(2b c)` (ii) `cosB(c^2+a^2-b^2)/(2a c)` (iii) (i) `cosC(a^2+b^2-c^2)/(2a b)`

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(Cosine Formulae) if a ,b ,c are the lengths of the sides opposite respectively to the angles A ,B ,C of a triangle A B C , show that (I) cosA=(b^2+c^2-a^2)/(2b c) (ii) cosB=(c^2+a^2-b^2)/(2a c) (iii) (i) cosC=(a^2+b^2-c^2)/(2a b)

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