網址: https://www.researchgate.net/publication/366445833/figure/fig6/AS:11431281108704836@1671567742076/The-spherical-vector-a-ex-v-is-an-oriented-angle-between-two-vectors-in-the.png
網址2: https://www.researchgate.net/figure/The-spherical-vector-a-ex-v-is-an-oriented-angle-between-two-vectors-in-the_fig6_366445833
