题目

The Man in Black and His Saving Grace In the mid-80s, Johnny Cash and June Cater Cash often appeared together in public. The man always in black had craggy face and piercing eyes a daunting way of turning aside reporters’ questions with a look or a curl of his lip. But all that changed with one disapproving glance from June. Where the Cashes were concerned, Johnny may have been large, but June was in charge. Their long sometimes beautiful, sometimes harrowing relationship throughout the late 1950s and mid-60s is the focus of Walk the Line, an Oscar-winning biopic. But it also explores 12．$\frac{sin40°\sqrt{1+cos80°}}{\sqrt{1-2sin10°cos10°}+sin10°}$的值为（　　）A．$\frac{1}{2}$B．$\frac{\sqrt{2}}{2}$C．$\sqrt{2}$D．$\sqrt{3}$