Hello, kmjt!

Your diagram is incorrect . . .

A plane is heading S 70° W with a groundspeed of 625 km/h.

If the pilot is steering west at an airspeed of 665 km/h,

. . what must be the windspeed and wind direction? Code:

665
A o - - - - - - - - - - - o O
\ 20° *
\ *
\ *
\ * 625
\ *
o
B

The plane is flying from O to A at 665 km/hr.

. .

The wind is blowing from A to B.

The plane's resultant flight is: . km/hr.

Law of Cosines: .

. . Hence: .

Then: .

. . Hnce: .

Therefore, the windspeed is 227.4 km/hr and its direction is: .S 20° E.

Interesting!

Triangle ABO is virtually a right triangle . . .

.