Question

In a triangle $\triangle ABC$, if $a$, $b$, and $c$ are in arithmetic progression, then $\cos A + 2\cos B + \cos C =$

• A. 1
• B. 2
• C. $\dfrac{3}{2}$
• D. $\sqrt{3}+1$

Hint:

For A.P. side problems, quickly verify with an equilateral triangle ($A=B=C=60^\circ$): $\cos 60^\circ + 2\cos 60^\circ + \cos 60^\circ = 0.5 + 1 + 0.5 = 2$. \checkmark

Answer 1

The Correct Option is B