若cosA-2sin(A-B)=0,求证:tan(A-B)=cosB/(sinB+2)
人气:463 ℃ 时间:2020-05-30 17:37:26
解答
cosA-2sin(A-B)=cos[A-B+B]-2sin(A-B)=cos[(A-B)+B]-2sin(A-B)
=cos(A-B)cosB-sin(A-B)sinB-2sin(A-B)=0
=> cos(A-B)cosB=sin(A-B)[sinB+2]
=> tan(A-B)=cosB/(sinB+2)
推荐
- 已知sina+sinb=1/2 tan(a+b)/2=2 求cosa+cosb
- sinA+sinB=1/2,tan[(A+B)/2]=2,求cosA+cosB
- 求证:cosa(cosa-cosb)+sina(sina-sinb)=2sin2a−b2.
- (1-cosA)/(1-cosB)=[2sin^2(A/2)]/[2sin^2(B/2)]=sinA/sinB=2sin(A/2)cos(A/2)/[2sin(B/2)cos(B/2)]
- sina+sinb=x,cosa+cosb=y,tan(a-b)/2=?
- 11 1317192329 的排列规律
- 电场中各点场强大小相同,而方向不同,存在这中电场吗?
- 什锦糖有奶糖酥糖水果糖按质量比2:3:5,有奶80克,酥140克,果170克,按质量比配什锦糖能配多少千克
猜你喜欢