f(x)=asinx+bcosx=√(a^2+b^2)sin(x+∆)tan∆=b/af(x)min=-√10,sin(x+∆) [-1,1]-> a^2+b^2=10f(π/4)=√2/2(a+b)=√2a+b=2 a=-1 b=3 f(x)=3cosx-sinxa=3 b=-1 f(x)=3sinx-cosx