Question

A distancia entre A (cos a, sen a ) e B (sen a , cos a ) é ?

Answer 1

$d=\sqrt{(x_b-x_a)^2+(y_b-y_a)^2}\\\\ d=\sqrt{(sena-cosa)^2+(cosa-sena)^2}\\\\ d=\sqrt{sen^2a-2senacosa+cos^2a+cos^2a-2senacosa+sen^2a}\\\\ d=\sqrt{2(sen^2a+cos^2a)-4senacosa}\\\\ d=\sqrt{2(1)-2sen2a}\\\\ \boxed{d=\sqrt{2(1-sen2a)}}$