问题
选择题
化简
|
答案
=1-2sin10°cos10° cos10°- 1-cos2170° sin210°-2sin10°cos10°+cos210° cos10°- 1-cos2170°
=
=(sin10°-cos10°)2 cos10°- sin2170°
=1cos10°-sin10° cos10°-sin10°
故选A
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化简
|
=1-2sin10°cos10° cos10°- 1-cos2170° sin210°-2sin10°cos10°+cos210° cos10°- 1-cos2170°
=
=(sin10°-cos10°)2 cos10°- sin2170°
=1cos10°-sin10° cos10°-sin10°
故选A