Question

不查表求值： ( 1 tan5° -tan5°)? 1 - cos20° 3 sin50° - ...

不查表求值： ( 1 tan5° -tan5°)? 1 - cos20° 3 sin50° - cos50° ．

Answer 1

( 1 tan5° -tan5°)? 1 - cos20° 3 sin50° - cos50° = ( cos5° sin5° - sin5° cos5° )? 1 - cos20° 3 sin50° - cos50° = cos10° sin10° ? 1 - cos20° 1 2 ( 3 sin50° - cos50°) = cos10° sin10° ? 1 - 1+2sin   2 10° sin20° =1． 故答案为：1．