Alight plane is headed due south with a speed relative to still air of 185 km/h. after 1 h, the pilot notices that they have covered only 135 km and their direction is not south but 75˚ south of east. what is the wind velocity?

Use the cosine rule to solve for the distance the wind pushed them to the east and because this all happened in an hour, you can say they travelled this distance per hour.

+-130 km due east which means the wind speed was +-130km/h.

So for example i used a^2=b^2+c^2-2bc(cos75) b will be the distance they travelled and c= 135cos75=35km now all you do is substitute in and you will get your distance that the wind pushed them to the east and because it was an hour of travel the distance as said before will be per hour.