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TS EAMCET · Maths · Properties of Triangles

In any \(\triangle A B C, a(b \cos C-c \cos B)\) equals

  1. A \(b^2+c^2\)
  2. B \(b^2-c^2\)
  3. C \(\frac{1}{b}+\frac{1}{c}\)
  4. D \(\frac{1}{b^2}-\frac{1}{c^2}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(b^2-c^2\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} a(b \cos C-c \cos B) & =a b \cos C-a c \cos B \\ & =\frac{a^2+b^2-c^2}{2}-\frac{a^2+c^2-b^2}{2} \\ & =b^2-c^2\end{aligned}\)