Find the solution of the initial-value problem M ·   x¨1(t) x¨2(t)   + K ·   x1(t) x2(t)   =   0 0   , where x1(0) = 1, x2(0) = 2, dx1 dt (0) = dx2 dt (0) = 0 and M =   1 2 2 2   , K =   4 8 8 2   . Is this periodic?

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations