Question

In a $△$ABC (c+a+b) (a+b-c)=ab. The measure of C is

• A.
• B.
• C.
• D. None of these

Answer 1

The correct option is C

$2s(2s-2c)=abors\left(\frac{s-c}{ab}\right)=\frac{1}{4}$
$orco{s}^2\frac{c}{2}=\frac{1}{4}orcos\frac{c}{2}=\frac{1}{2}$
$\Rightarrow \frac{c}{2}={60}^o\Rightarrow c=\frac{2\pi }{3}$