①氏戚 √2/2② AB=8③ b=√3④f(x)=sin2x+cos2x=√2*sin(2x+π/4)周唯核辩期:T=2π/2=π最大指缺值: √2f(θ+π/8)=√2/2√2*sin[2(θ+π/8)+π/4]=√2/3cos2θ=1/3θ为锐角sin2θ=2√2/3, tan2θ=2√2