Answer:
51°, 129°
Step-by-step explanation:
The ratio of the sides is the tangent of the angle a diagonal makes with the side of the rectangle. The smaller such angle will be
arctan(12.4/26) ≈ 25.5°
The smaller of the angles between the diagonals will be twice this value, or 51°. Its supplement is the larger angle between the diagonals, 129°.
