solve( [0 = 1/2 * (2/5 * M * R^2) * omega^2 + 1/2 * M * v^2 - M * g * h, v = R * omega], [omega, v]);
cross( u, v ):= [ u[2]*v[3] - u[3]*v[2], u[3]*v[1] - u[1]*v[3], u[1]*v[2] - u[2]*v[1] ]; cross( [2,3,0], [-1,2,0] ); cross( [-1,2,0], [2,3,0] );
solve(( 1/2 * 100 * 2^2 + 60 * 2^2 ) * 2 = (1/2*100*2^2 + 60 * 0.5^2) * omega, omega);[rad] を得る。
cross( [6,2,-1], [2,-1,-3]);