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

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

(2sin5°-cos25°)\(cos65°)=?（ 根号下1-2sin10°cos10°)\(根号下1-cos^2170°-cos350°)=?
(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））/(cos65°)
=-√3