Question

prove that a(b cosC-c cosB)= b^2-c^2​

Answer 1

Step-by-step explanation:

triangle abc prove that a(bcosC-ccosB)=b^2-c^2. law of cosines: c² = a² + b² - 2ab cos y. converting equation in law of cosines. b^2 = a^2 + c^2 - 2ac cos B. c^2 = a^2 + b^2 - 2ab cos C. Second equation is subtracted from the first one. and the result came. b^2 - c^2 = c^2 - b^2 - 2ac cos B + 2ab cos C.