epicycloid

/ep-uh-sahy-kloid/US // ˌɛp əˈsaɪ klɔɪd //UK // (ˌɛpɪˈsaɪklɔɪd) //

蜉蝣,蜉蝣蝣

Definitions

n.名词 noun

1
Geometry.
- : a curve generated by the motion of a point on the circumference of a circle that rolls externally, without slipping, on a fixed circle. Equation: x = cos − b cos[θ/b] and y = sin − b sin[θ/b].

The epicycloid shown is termed the “three-cusped epicycloid” or the “epicycloid of Cremona.”
External epicycloid, described by a circle rolling about a fixed circle inside of it.
The curve may be regarded as an epitrochoid (see Epicycloid) in which the rolling and fixed circles have equal radii.
It follows that a line from B to M will always be tangential to the epicycloid.
Cycloid External epicycloid, described by a circle rolling about a fixed circle inside of it.