Answer:
The red arrow shows the resultant vector. We have a Side Angle Side triangle ABC so can use The Cosine Rule:
a2=b2+c2−2bccosA
This becomes:
R2=7002+402−(2×700×40×cos45)
R2=491,600−39,597.9
R=672.3xkm/hr
This is the groundspeed of the aircraft.
To find θ we can use The Sine Rule:
sinCc=sinAa
This becomes:
sinθ40=sin45672.3
sinθ=0.04207
θ=2.41∘
This is known as the drift angle and is the correction the pilot should apply to remain on course.
The heading is the direction the aircraft's nose is pointing which is 000∘.
The track is the actual direction over the ground which is 357.6∘
An alternative method to this would be to separate each vector into vertical and horizontal components and add.
The resultant can be found using Pythagoras.