已知p/2
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/14 17:31:01
![已知p/2](/uploads/image/z/10281385-1-5.jpg?t=%E5%B7%B2%E7%9F%A5p%2F2)
xݓ;N@?6ƾHCE,r*(HD" 9y"$pc̿!Omz|?wܳy=; BDoe^ą(0~,߅SRm@"-bUGuThpl
2r BL"(Y֥CNqeg-Idb[Xe" >ȳ~ZM(ݏ6gׄin̐>-J
ɀhBϡ0'|`~
5ΏQ[,>jmrXJe+imW/7pzU6j@
已知p/2
已知p/2
已知p/2
π/20
=sin(a+b)cos(a-b)+cos(a+b)sin(a-b)
= -3/5 *12/13 -4/5 * 5/13
= - 56/65
sin2a=sin[(a+b)+(a-b)]
=sin(a+b)cos(a-b)+sin(a-b)cos(a+b)
cos(a-b)=12/13
p/2p>a-b>0
sin(a-b)=√[1-(12/13)^2]
=5/13
p/2p
全部展开
sin2a=sin[(a+b)+(a-b)]
=sin(a+b)cos(a-b)+sin(a-b)cos(a+b)
cos(a-b)=12/13
p/2p>a-b>0
sin(a-b)=√[1-(12/13)^2]
=5/13
p/2pcos(a+b)=-√[1-sin(a+b)^2]
=-√[1-(-3/5)^2]
=-4/5
sin2a=(-3/5)*(12/13)+(5/13)*(-4/5)
=(-36-20)/65=-56/65
收起