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