17/11/26 10:56:08.99 b02GGEMo.net
>>23
r =｛sin(θ/4)}^4,
dr/dθ =｛sin(θ/4)}^3・cos(θ/4),
(長さ）= ∫ √{r^2 +（dr/dθ)^2｝dθ
= ∫｛sin(θ/4)}^3 dθ
= ∫｛３sin(θ/4）- sin(3θ/4)}/4 dθ
= 8/3 -３cos(θ/4）+（1/3)cos(3θ/4),
θ=π のとき (8-5√2)/3 = 0.309644
17/11/26 10:56:08.99 b02GGEMo.net
>>23
r =｛sin(θ/4)}^4,
dr/dθ =｛sin(θ/4)}^3・cos(θ/4),
(長さ）= ∫ √{r^2 +（dr/dθ)^2｝dθ
= ∫｛sin(θ/4)}^3 dθ
= ∫｛３sin(θ/4）- sin(3θ/4)}/4 dθ
= 8/3 -３cos(θ/4）+（1/3)cos(3θ/4),
θ=π のとき (8-5√2)/3 = 0.309644