" 28.If "x=a'cos theta+log t(tan(y)/(2)|" and "y=a sin theta" find "(dy)/(dx)" at "(pi)/(4)

If x=a(cos theta+log tan((theta)/(2))) and y=a sin theta then find (dy)/(dx) at theta=(pi)/(3) and theta=(pi)/(4)

If x=a(cos t+(1)/(2)log tan^(2)t) and y=a sin t then find (dy)/(dx) at t=(pi)/(4)

If x = a(cos theta + log tan(theta/2)), y = a sin theta find dy/dx at theta = pi/3

If x=-a cos theta and y= a sin theta , find (dy)/(dx) .

If x = a cos theta and y = b sin theta , find (dy)/(dx)

If x = a cos theta and y = b sin theta , find (dy)/(dx)

If x=cos theta-cos 2theta and y=sin theta-sin2theta , then find (dy)/(dx) .

If x=a sec^(2)theta and y=a tan^(3) theta, " find " (dy)/(dx)" at " theta=(pi)/(4) .

If x = a[cos t + log tan (t/2)], y = a sin t then find (dy)/(dx) .