I could really use some help on this practice test to prepare me. I don't remember how to perform alot of this so if you could explain it thoroughly it would be appreciated:)

20. Determine if the graph is symmetric about the x-axis, the y-axis, or the origin.

r = 4 cos 3

19. A railroad tunnel is shaped like a semiellipse, as shown below. (Graph is a half circle on the positive side of x axis- looks like a sunset)

A semiellipse is shown on the coordinate plane with vertices on the x axis and one point of intersection with the positive y axis.

The height of the tunnel at the center is 35 ft, and the vertical clearance must be 21 ft at a point 8 ft from the center. Find an equation for the ellipse.

18. Determine if the graph is symmetric about the x-axis, the y-axis, or the origin.

r = 2 + 3 sin

17. The graph of a limacon curve is given. (perfect circle, no indentations) Without using your graphing calculator, determine which equation is correct for the graph.

a circle symmetric to the y axis where the majority of the circle lies in quadrants one and two

[-5, 5] by [-5, 5]

16. Find the rectangular coordinates of the point with the polar coordinates.\

(-5, 5pi/3)

15. Eliminate the parameter.

x = 1/2t, y = 3t^3 - 1

14. Find an equation in standard form for the hyperbola with vertices at (0, 4) and asymptotes at y = 1/4x

13. Find an equation in standard form for the hyperbola with vertices at (0, 9) and foci at (0, 10).

8. Find an equation in standard form for the ellipse with the vertical major axis of length 16 and minor axis of length 4.