已知函数f(x)=Asin(2x+β)(A>0,|β|<π/2),且f(5π/6)=-A

问题描述:

已知函数f(x)=Asin(2x+β)(A>0,|β|<π/2),且f(5π/6)=-A
求β的值
若f(a)=(3/5)A,f(β+π/12)=(5/13)A,且π/6<α<π/3,0<β<求π/4,求cos(2α+2β-π/6)的值

f(5π/6)=-A的意思是
当x=5π/6时,2x+β取到3π/2+2kπ,k∈z
β=-π/6