2sinC=4sin(C/2)cos(C/2)

Cos(C/2) is not 0, so sin (c/2) 2 = 1/4, and sin (c/2) = 1/2.

C/2

2. Sine theorem: AB/sinC=BC/sinA=AC/sinB= perimeter /(sinA+sinB+sinC)=2/ root 3.

Sina+sin b+sinc = Sina+sin( 120-A)+root 3/2 = 3/2 Sina+root 3/2 cosa+root 3/2 = root 3 cos(A-60)+root 3/2 *

Where 0

So 2