For the following questions answer them individually
If the triangle PQRvaries, then the minimum value of $$\cos(P+Q)+\cos(Q+R)+\cos(R+P)$$ is
Let p,q be integers and let $$\alpha,\beta$$ be the roots of the equation, $$X^{2}-x-1=0$$, Where $$\alpha\neq\beta$$. For n=0,1,2..., Let $$a_{n}=p\alpha^{n}+q\beta^{n}$$.
FACT: If a and b are rational numbers and $$a+b\sqrt{5}=0$$, then $$a=0=b$$.