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TS EAMCET · Maths · Properties of Triangles

In a \(\triangle A B C\), if \(a \cos ^2 \frac{C}{2}+c \cos ^2 \frac{A}{2}=\frac{3 b}{2}\), then

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

Answer & Solution

Correct Answer

(A) \(2 b=a+c\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \text { Given, } a \cos ^2 \frac{C}{2}+c \cos ^2 \frac{A}{2}=\frac{3 b}{2} \\ & \Rightarrow a(1+\cos c)+c(1+\cos A)=3 b \\ & \Rightarrow a+c+(a \cos C+c \cos A)=3 b \\ & \Rightarrow(a+c)+b=3 b \Rightarrow a+c=2 b\end{aligned}\)