In ||gm ABCD, A and C are at right angles to each other. ∴ ∠A = ∠C= 140° But ∠A = ∠C (opposite angles) ∴ ∠A = ∠C= 140°/2= 70° But ∠A + ∠B = 180° (sum of adjacent angles) => 70° + ∠B = 180° => ∠B = 180° – 70° = 110° But ∠ D = ∠ B (opposite angles) ∴ ∠D = 110° So, A is 70°, B is 110°, C is 70°, and D is 110°.