TS EAMCET · Maths · Trigonometric Ratios & Identities
In a \(\triangle A B C\), if \(\cos A+\cos B+\cos C\) \(=a+b \sin \frac{A}{2} \sin \frac{B}{2} \sin \frac{C}{2}\), then \((a+b)\) is equal to
- A 3
- B 0
- C 1
- D 5
Answer & Solution
Correct Answer
(D) 5
Step-by-step Solution
Detailed explanation
\(A, B, C\) are angles of a triangle. \[ \begin{aligned} & \therefore A+B+C=180^{\circ} \Rightarrow A+B=180^{\circ}-C \\ & \Rightarrow \quad \frac{A+B}{2}=90^{\circ}-\frac{C}{2} \end{aligned} \] Now, \(\cos A+\cos B+\cos C\)…
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