Convert the rectangular equation to polar form. Assume

a > 0.

x^2 + y^2 - 9ax=0

just crank it out

r^2 - 9arcosθ = 0
r = 9a cosθ
you know it's just a circle with center at (9a/2,0) and radius 9a/2.

To convert the given rectangular equation to polar form, we need to express the variables x and y in terms of the polar coordinates r and θ.

In polar coordinates, x and y are related to r and θ as follows:
x = r * cos(θ)
y = r * sin(θ)

Now let's substitute these expressions into the given equation:

x^2 + y^2 - 9ax = 0
(r * cos(θ))^2 + (r * sin(θ))^2 - 9a(r * cos(θ)) = 0

Expanding and simplifying this equation gives us:

r^2 * cos^2(θ) + r^2 * sin^2(θ) - 9a * r * cos(θ) = 0
r^2 * (cos^2(θ) + sin^2(θ)) - 9a * r * cos(θ) = 0

Using the trigonometric identity cos^2(θ) + sin^2(θ) = 1, the equation simplifies further:

r^2 - 9a * r * cos(θ) = 0

Now, we have the polar form of the equation:

r^2 - 9a * r * cos(θ) = 0

This is the transformation of the given rectangular equation to polar form.