kill(all)$

load(ntrig)$ load(atrig1)$

van=facebook.com/LearningCalculus$

b:((((((r*(-1))+(((r*(-1))+(((sin(α)*r*(-2))+(cos(α)*sin(α)*(r)^(2)*(-2)))*((sin(α)*2)+(cos(α)*sin(α)*r*2))*((4+((sin(α))^(2)*(r)^(2)*4)))^((-1))*(-2)))*(-1))+(cos(α)*2)+((cos(α))^(2)*r*2)))^(2)+(((((sin(α)*r*(-2))+(cos(α)*sin(α)*(r)^(2)*(-2)))*(r+(((r*(-1))+(cos(α)*2)+((cos(α))^(2)*r*2))*(-1)))*((4+((sin(α))^(2)*(r)^(2)*4)))^((-1))*2)+(sin(α)*2)+(cos(α)*sin(α)*r*2)))^(2)))^(1/2));

d1:trigsimp(%);

d1;

((((1+((sin(α))^(2)*(r)^(2))))^((-1/2))*((1+((sin(α))^(2)*(-1))+((sin(α))^(4)*(r)^(2))+(cos(α)*(sin(α))^(2)*r*(-2))))^(1/2)*r*2));

d2:trigsimp(%);

solve(d1=d2,cos(α));

trigsimp(%);