Triangle related question

Submitted by alpha on Wed, 07/15/2009 - 16:47.

In a triangle PQR , angle R=pi/2 .It tan(P/2)and tan(Q/2) are the roots of the equation $ax^2+bx+c=0,(a\ne0)$ , then
a)a+b=c
b)b+c=a
c)a+c=b
d)b=c