Asiny + Bcosy
= √(A² + B²)[(siny)A/√(A² + B²) + (cosy)B/√(A² + B²)]
= √(A² + B²)[(siny)cosφ + (cosy)sinφ],其中tanφ =B/A,令a = √(A² + B²)
= √(A² + B²)sin(y + φ)
= asin(y + φ)
dy/dx = asin(y + φ)
d(y + φ)/sin(y + φ) = adx
lntan[(y + φ)/2] = ax + c
tan[(y + φ)/2] = Ce^(ax)
y = 2arctan[Ce^(ax)] - φ