Most likely sinusoid.
A parabolic curve is a curve where any point in the curve is an equal distance from two areas. It is an equal distance away from the focus, or fixed point and the fixed straight line, or the directrix.
An ellipse is a conic section, a curving line which is the path of a point that moves in such a way that the sum of its distance from two fixed points is constant.... so no - there are not 4 straight angles in an ellipse, nor any straight bits at all.
straight
A line is a straight path that extends infinitely or endlessly in opposite directions. A straight path that joins two points is called a line segment.
Unlike air travel, they need a fixed land path. Unlike trucking, they need a fixed land path.
With a curved path you have to slow down to curve as with a straight path you dont have to slow down you can do as fast as you need to go to get threw it.
straight
light takes a straight path.
The symbol for Straight Path Communications Inc. in the AMEX is: STRP.
The cast of A Straight Path - 1911 includes: Jane Fearnley
Straight line