Multivariable Calculus · free preview

New Coordinate Systems

Polar coordinates in the plane and their extensions to cylindrical and spherical coordinates in space, with conversion formulas and the art of matching coordinates to symmetry.

1. Polar coordinates describe the plane by distance and direction

Polar coordinates describe the plane by distance and direction

2. Cylindrical coordinates stack height on polar coordinates

Cylindrical coordinates stack height on polar coordinates

3. Spherical coordinates measure from the origin in one distance and two angles

Spherical coordinates measure from the origin in one distance and two angles

4. Match the coordinate system to the symmetry of the problem

Match the coordinate system to the symmetry of the problem

5. Converting a planar point to polar coordinates

Convert the Cartesian point (−3,4)(-3, 4) to polar coordinates (r,θ)(r, \theta) with r>0r > 0 and 0≤θ<2π0 \le \theta < 2\pi. Which answer is correct?

6. Cylindrical to Cartesian

A point has cylindrical coordinates (3,π2,−2)\left(3, \tfrac{\pi}{2}, -2\right). Which Cartesian point does it name?

7. Spherical to Cartesian

A point has spherical coordinates ρ=4\rho = 4, ϕ=π3\phi = \tfrac{\pi}{3}, θ=π6\theta = \tfrac{\pi}{6}. Which Cartesian point does it name?

8. Choosing coordinates from the region

A solid region is described by x2+y2≤9x^2 + y^2 \le 9 and 0≤z≤40 \le z \le 4. Which coordinate system makes the bounds of this region simplest?

9. The radial coordinate of a cylindrical point

Convert the Cartesian point (2,2,5)(2, 2, 5) to cylindrical coordinates and give just the radial coordinate rr, in the form a*sqrt(b) with integers, like 2*sqrt(3).

10. The polar angle of a point on the axis

Convert the Cartesian point (0,0,5)(0, 0, 5) to spherical coordinates and give just the polar angle ϕ\phi measured from the positive zz-axis, as a number of radians.

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