In a right triangle, the sum of the angles is always 180 degrees. Given that angle G is a right angle (90 degrees) and angle O is 41 degrees, we can find angle D by using the following calculation:
Angle D = 180° - Angle G - Angle O
Angle D = 180° - 90° - 41°
Angle D = 180° - 131°
Angle D = 49°
Thus, the measure of the angle at point D is 49 degrees.