cos25°*cos(α-25°)-cos65°*sin(α-25°)
(2sin5°-cos25°)\(cos65°)=?( 根号下1-2sin10°cos10°)\(根号下1-cos^21
cos65°-sin80°sin15°/cos5°-co..
求值sin25π/6+cos25π/3+tan(-25π/4)+sin(-7π/3)×cos(-13π/6)-sin(-
Cos(180°+α)*sin(α+360°)/sin(-α-180°)*cos(-180°-α)
用和(差)角公式求下列各式的值:(1)sin70°cos25°-sin20°sin25°;(2)cos^2 15°-si
sinα+cosβ=sin225° sinα-cosβ=cos225°求cos(α-β)及cos(α+β)
-cos(α-45°)=sin(α+45°)对吗?
化简cos^2(-α)-[tan(360°+α)/sin(-α)]
化简,cos²(-α)-tan(360°+α)/sin(-α)
已知sinαcosα= ,且0°
已知sinαcosα=0.125,且0°
化简cos(540°-α)sin(α-360°)/sin(-α+180°)cos(180°+α)