Thursday Morning Riddle

I invert any trig function back where it came;
I am Joan La Pucelle by her better-known name;
How a plot will develop as writers would frame;
And a slice of circumference with angle the same.

Who am I?

UPDATE: Riddle solved by Bronx Richie. See comments for answer.

2 Responses to “Thursday Morning Riddle”

  1. Bronx Richie Says:

    arc

  2. Bill Says:

    ARC is correct. Way to go, Bronx Richie!

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