>>629
Wolfram先生

https://www.wolframalpha.com/input/?i=plot+x%3Dsin(t),+y%3D((1%2Bcos(t))%2Fsin(t)+-+2*cos(t)),+from+pi%2F6+to+5*pi%2F6

https://www.wolframalpha.com/input/?i=integrate(2*cos(t)*((1%2Bcos(t))%2Fsin(t)+-+2*cos(t)),t,5*pi%2F6,pi%2F6)