化简计算cos(80°+3α)cos(35°+α)+sin(80°+α)cos(55°-α)的过程?
cos(α+β)=cosαcosβ+sinαsinβ的证明过程
怎样化简cosαcos(60°-α)+1
化简sin(80°+3α)cos(35°+α)-cos(80°﹢3α﹚sin﹙35°﹢3α﹚
Cos(180°+α)*sin(α+360°)/sin(-α-180°)*cos(-180°-α)
sinα+cosβ=sin225° sinα-cosβ=cos225°求cos(α-β)及cos(α+β)
.[1/cos(-α)+cos(180°+ α )]/[1/sin(540°-α)+sin(360°-α)]=tan^3
sinα + cosα
求sinα-cosα>0 sinα-cosα<0的证明过程
已知tanα=1/3,计算(1)sinα+2cosα/5cosα-sinα,(2)1/2sinαcosα+cos^α
已知sinα+3cosα=2,求(sinα-cosα)/(sinα+cosα)的值
化简cos^2(-α)-[tan(360°+α)/sin(-α)]
化简,cos²(-α)-tan(360°+α)/sin(-α)