a$)$ Find a Cartesian equation for the curve described by the given polar equation.

$r=3sin$

b$)$ Find the polar equation for the curve represented by the given Cartesian equation.

$x+y=4$

c$)$ Find an equation of the tangent to the curve at the point corresponding to the given value of the parameter.

$x=tcost,y=tsint,t=-$

d$)$ Sketch the parametric curve and eliminate the parameter to find the Cartesian equation of the curve.

$x=cos,y=sec,0<mfrac><mrow><mi></mi></mrow><mrow><mn>2</mn></mrow></mfrac>$

e$)$ The graph of the following curve is given. Find the area that it encloses.

$r=2+cos6$