tan(a+π/4)=k,则cos2a=?

来源：学生作业帮助网编辑：作业帮时间：2024/05/10 14:06:09

tan(a+π/4)=k,则cos2a=?
tan(a+π/4)=k,则cos2a=?

tan(a+π/4)=k,则cos2a=?
tan(a+π/4)
=(tana+tanπ/4)/(1-tanatanπ/4)
=(tana+1)/(1-tana)
=k
∴tana=(k-1)/(k+1)
cos2a
=cos²a-sin²a
=(cos²a-sin²a)/1
=(cos²a-sin²a)/(cos²a+sin²a)
分子分母同除cos²a得
=(1-tan²a)/(1+tan²a)
=(2k)/(k²+1)
手机提问的朋友在客户端右上角评价点【满意】即可

根据二倍角公式tan（2a）=(2tan a)/(1-tana*tana) 求出tan（2a+π/2）=-cot(2a) 即tan（2a）和cot（2a）然后自己在草稿纸上画三角形草稿可以求出cos2a=(2*k)/(k*k+1)

tan(a+π/4)=k,则cos2a= tan(a+π/4)=k,则cos2a=? tan(a+π/4)=2,则cos2a+3sin^2a+tan a= 已知tan(π-a)=-1/2,则cos2a= 已知TAN(A+4/π)=2怎cos2A=? tan(π/4+a)=3,求sin2a-2cos2a tan(a+π/4)=2cos2a 怎么化简 cos2a/tan(π/4+a), 已知tan(a+派／4)＝2,则cos2a= tan(a+π/4)=2,则(sin2a-cos²a)/(1+cos2a)=? tan(a+π/4)=2,则cos2a+3sin^2a+tan2a= tan(a+π/4)=3+2倍根号2,则1-cos2a/sin2a= 已知tan(π/4-a)=-1/2,则cos2a= 若tan(a+3π/4)=2011,则1/cos2a+tan2a=?没思路, 有好评, tan(π/4-A)=3,则cos2A/(1+sin2A)= 已知tan（π/4+a）=3,则2sina*cosa-1-cos2a=? 已知tan(a+π/4)=1/3,则（sina-cosa)^2/cos2a 求证(1+sin2a-cos2a)/(1+sin2a+cos2a)=tan a