Question 921133
I'll get you started



{{{9*sin(t) - cos(t)=0}}}



{{{9*sin(t) = cos(t)}}}



{{{81*sin^2(t) = cos^2(t)}}}



{{{81*sin^2(t) = 1-sin^2(t)}}}



{{{81*sin^2(t)+sin^2(t) = 1}}}



{{{82*sin^2(t) = 1}}}



and I'll let you finish up from here.