Question

If the sides of a ∆ ABC are in A.P. and a is the smallest side, then cos A equals:

• A.
• B.
• C. $\frac { 4 c - 3 b } { 2 c }$
• D. None of these

Answer 1

Answer: (C)

$\frac { 4 c - 3 b } { 2 c }$

Answer 2

∴ 2b = a + c

∴ cosA = $\frac { \mathrm { b } ^ { 2 } + \mathrm { c } ^ { 2 } - \mathrm { a } ^ { 2 } } { 2 \mathrm { bc } }$

= cosA =