唔識做M2數學,請幫幫忙!! (1)

(1) u = (1, 8) - (- 4, 0) = ( 5, 8)
v = (7, 7) - (2, - 1) = (5, 8)
so u = v.
(2)
Vector A = (180 cos x , 180 sin x)
Vector B = (275, 0)
so A + B = ( 180 cos x + 275, 180 sin x)
(3)
Speed of airplane in vector form = (400, 0)
Speed of wind = (- 50 cos 45, 50 sin 45)
So resultant speed = ( 400 - 50 cos 45, 50 sin 45)
= (364.64, 35.35)
so speed = sqrt ( 364.64^2 + 35.35^2) = 366.35 mph.
Direction = arctan ( 35.35/364.64) = 5.5 degree = N 84.5 E.