Parametric equations and polar coordinates

Practice sheet

Fresh questions from the whole chapter, to do on paper.

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  1. x(t)=t+1x(t) = t + 1 and y(t)=t2y(t) = t^2. Tap the point where the curve is at t=1t = 1.
  2. x(t)=4t+4x(t) = 4t + 4 and y(t)=t−1y(t) = t - 1. At what time tt does the point have x=8x = 8?
  3. x=t+6x = t + 6 and y=t2y = t^2. Write yy in terms of xx.
  4. x=3tx = 3t and y=4t+9y = 4t + 9. Write yy in terms of xx.
  5. What curve do x=5cos⁡tx = 5\cos t and y=5sin⁡ty = 5\sin t draw, for 0≤t<2π0 \le t < 2\pi?
    1. A circle of radius 5 centered at the origin
    2. A line
    3. A circle of radius 2525
  6. The ellipse x=3cos⁡tx = 3\cos t, y=4sin⁡ty = 4\sin t reaches xx-values from −c-c to cc. What is cc?
  7. A point moves on x=7sin⁡tx = 7\sin t, y=7cos⁡ty = 7\cos t. At t=0t = 0 it is at (0,7)(0, 7). Which way does it go as tt increases?
    1. Clockwise
    2. Counterclockwise
    3. Along a straight line
  8. A point moves on x=8cos⁡(4t)x = 8\cos(4t), y=8sin⁡(4t)y = 8\sin(4t). How long does one full turn take?
  9. Tap the point with polar coordinates (4,3π2)\left(4, \frac{3 \pi}{2}\right).
  10. What is the graph of the polar equation r=5r = 5?
    1. A circle of radius 5 centered at the origin
    2. A line through the origin
    3. The vertical line x=5x = 5
  11. The polar equation r=12sin⁡θr = 12\sin\theta is a circle. In rectangular coordinates, it is x2+y2=12yx^2 + y^2 = 12y. What is the yy-coordinate of its center?
  12. The polar equation θ=π6\theta =\frac{\pi}{6} is a line through the origin. What is its slope?