(2sin5°-cos25°)\(cos65°)=?（根号下1-2sin10°cos10°)\(根号下1-cos^2170°-c_数学解答

(2sin5°-cos25°)\(cos65°)=?（根号下1-2sin10°cos10°)\(根号下1-cos^2170°-cos350°)=?

人气：216 ℃　时间：2019-10-13 09:23:26

解答

(2sin5°-cos25°)\(cos65°)=(2sin5°-cos(30-5)°)\(cos65°)=(2sin5°-(√3/2cos5°+1/2sin5°)\(cos65°)=（3/2sin5°-√3/2cos5°）/(cos65°)=√3（√3/2sin5°-1/2cos5°）/(cos65°)=-√3（sin（30-5））/(c...