问题
解答题
不查表求值：(
|
答案
(
-tan5°)•1 tan5°
=(1 - cos20°
sin50° - cos50°3
-cos5° sin5°
)•sin5° cos5° 1 - cos20°
sin50° - cos50°3
=
•cos10° sin10°
=1 - cos20°
(1 2
sin50° - cos50°)3
•cos10° sin10°
=1．1 - 1+2sin 210° sin20°
故答案为：1．