Answer:
y-axis
Step-by-step explanation:
The function graph is symmetric about
- the y-axis when it is an even function
- the origin when it is an odd function.
A symmetrical graph about the x-axis is not a function graph.
f(x) is an even if and only if f(-x) = f(x).
f(x) is an odd if and only if f(-x) = -f(x).
We have the function r(θ) = 4cos(5θ)
(olny symmetry about the y-axis or about the origin)
Check r(-θ):
r(-θ) = 4cos(5(-θ)) = 4cos(-5θ) = 4cos(5θ)
used cos(-x) = cos x
We have r(-θ) = r(θ). Therefore the graph of r(θ) is symmetric about the y-axis.
