Polar Area Plots

I am really confused about how polar plots work and am not seeing what I expect at all. For example

import plotly.graph_objs as go
from plotly.offline import plot

traces = [go.Area(r=[1, 1], t=[10, 30], name="Area")]
plot(traces)

Produces the following:

I would expect to see either one of two things. A wedge from 0 to 10 degrees of radial length 1 and a second wedge from 0 to 30 degrees of radial length 1, or a single wedge from 10 to 30 degrees of radial length 1. Instead from the picture it looks like Im getting a single wedge from 315 to 45 degrees of radial length 13.