sin²75°-1 的值为

1. A.
   
2. B.
   -
3. C.
   
4. D.
   

A.               B.                 C.             D.1

A.2                                                                 B.

C.1                                                                 D.

A.1                              B.0                              C.－1                           D.±1

A.1                          B.                         C.0                          D.－1