Question

Which is the parametric form of the polar equation r=-4 theta?

A. x=-4 cos theta, y=-4 sin theta
B. x=-4 theta cos theta, y=-4 theta sin theta
C. x=-theta cos theta, y=-theta cos theta

Answer 1

C) x = -4θcosθ and y = -4θsinθ

Explanation:

Other person was wrong.

Answer 2

Answer: Option B.

Explanation:

we have that r = 4*θ

(you writted a negative equation, but we can never have a negative radius)

We also have that:

r = √(x^2 + y^2) = 4*θ

We can use the relationship cos(x)^2 + sin(x)^2 = 1

and write X = A*cos(θ) and Y = A*sin(θ)

and now we have:

r = √( (A*cos(θ))^2 + (A*sin(θ))^2) = √(A)^2 = 4*θ

So the correct option is:

x = 4*θ*cos(θ) or -4*θ*cos(θ)

y = 4*θ*sin(θ) or -4*θ*cos(θ)

(We can have the positive or negative options because we are squaring the term, so the sign does not matter)

The correct option then is B