sin(A+B)sin(A-B)
=(sinAcosB+sinBcosA)*(sinAcosB-sinBcosA)
=(sinAcosB)^2-(sinBcosA)^2
=((sinA)^2)*(1-(sinB)^2)-((sinB)^2)*(1-(sinA)^2)
=(sinA)^2-(sinB)^2
“^”是次方的意思
“*”是乘号的意思
sin(A+B)sin(A-B)
=(sinAcosB+sinBcosA)*(sinAcosB-sinBcosA)
=(sinAcosB)^2-(sinBcosA)^2
=((sinA)^2)*(1-(sinB)^2)-((sinB)^2)*(1-(sinA)^2)
=(sinA)^2-(sinB)^2
“^”是次方的意思
“*”是乘号的意思