x2=sin(a+b)*h
y2=cos(a+b)*h

=>

x2=(sin(a)*cos(b)+cos(a)*sin(b))*h
y2=(cos(a)*cos(b)+sin(a)*sin(b))*h

=>

x2=(x1/h*cos(b)+y1/h*sin(b))*h
y2=(y1/h*cos(b)-x1/h*sin(b))*h

=>

x2=x1*cos(b)+y1*sin(b)
y2=y1*cos(b)-x1*sin(b)