1]the equation$\displaystyle 1-\cos^ x + \sinx\cosx = k$ then there exists real solution when k belongs to

A)$\displaystyle 0<k<\frac{1+\sqrt2}{2}$

B)$\displaystyle 2-\sqrt3 < k 2+\sqrt3$

C)$\displaystyle 0<k<2-\sqrt3$

D)$\displaystyle \frac{1-\sqrt2}{2} < k < \frac{1+\sqrt2}{2}$

2]let a,b belong to the set [0,$\displaystyle \frac{\pi}{2}$] if

$\displaystyle sin^6 a+3\sin^2 a\cos^2 a+\cos^6 b=1$

then $\displaystyle \frac{255a+b}{a+b} =?$