首先得T/2=2π-3π/4=5π/4
所以:T=5π/2,即2π/w=5π/2,所以:w=4/5;
所以:y=sin(4x/5+A),把点(3π/4,-1)代入,得:-1=sin(-3π/5+A)
所以:-3π/5+A=-π/2+2kπ,得:A=π/10+2kπ,
因为:-π
首先得T/2=2π-3π/4=5π/4
所以:T=5π/2,即2π/w=5π/2,所以:w=4/5;
所以:y=sin(4x/5+A),把点(3π/4,-1)代入,得:-1=sin(-3π/5+A)
所以:-3π/5+A=-π/2+2kπ,得:A=π/10+2kπ,
因为:-π