Question 1187939
If you draw this, 4 minutes at 90 km/60 minutes (1.5 km/min) means the glider is 6 km east. That is the ground leg.
The altitude is 2 km, the vertical leg.
The angle of elevation is the tangent of theta, which is opposite/adj to 2/6 or 0.3333
tan^-1 (0.3333)=14.43 degrees