Advanced Calculus(MATH 104)-Polar Coordinates
Harish Bhandari
Department of Mathematics
Kathmandu University
Dhulikhel, Nepal
Lecture 4
August 10, 2019
Cylindrical Coordinates
Definition
Cylindrical coordinate represent a
point P in space by ordered triples
(r , θ, z) in which
i. r and θ are polar coordinate for
the vertical projection of P on
xy plane.
ii. z is rectangular vertical
coordinate.
Relation between rectangular and cylindrical coordinates
Harish Bhandari Coordinates systems
Note
What does following represent in
cylindrical coordinate system?
i. r = a
ii. r = 0
iii. θ = θ0
iv. z = z0
Explanations
i. Cylinder about z-axis
ii. z-axis
iii. Plane containing z-axis, making angle θ0 with x-axis
iv. Plane perpendicular to z-axis
Harish Bhandari Coordinates systems
Harish Bhandari Coordinates systems
Examples
Find the rectangular Find the cylindrical
coordinates from the coordinates from the
following cylindrical following rectangular
coordinates: coordinates:
√
i. (4, π6 , 3) a. (1, 3, 2)
ii. (3, π3 , 5) b. (1, 1, 5)
iii. (4, 7π c. (3, −3, 7)
6 , 3) √ √
iv. (2, π, −4) d. (−2 2, 2 2, 4)
Exercise
a. Find the cartesian
form of
z = r 2 (Paraboloid)
b. Find the circular
cylinder in
cylindrical
coordinate:
4x 2 + 4y 2 = 9
Harish Bhandari Coordinates systems
Spherical Coordinates
Definition
Cylindrical coordinate represent a point P in space by ordered
triples (ρ, θ, φ) in which
i. ρ is the distance of P from origin.
~ makes with positive z-axis (0 ≤ φ ≤ π).
ii. φ is the angle OP
iii. θ is the angle from cylindrical coordinates.
Harish Bhandari Coordinates systems
Note
What does following represent in
spherical coordinate system?
i. ρ = a
ii. φ = φ0
iii. θ = θ0
iv. φ = φ0 > π2
Explanations
i. Sphere of radius a centered at origin.
ii. Cone, vertex at origin, axis along z-axis
iii. Half plane containing z-axis, making angle θ0 with positive
x-axis
iv. Cone open downwards
Harish Bhandari Coordinates systems
Relations of spherical coordinates
Spherical coordinates and rectangular coordinates
Spherical coordinates and Cylindrical coordinates
Harish Bhandari Coordinates systems
Relations of spherical coordinates
Harish Bhandari Coordinates systems
Example
1. Find the spherical coordinate equation for
a. x 2 +p
y 2 + (z − 1)2 = 1
b. z = x 2 + y 2
√
2. Find the spherical coordinates for (0, 2 3, −2)
Harish Bhandari Coordinates systems