DRDO Multi tasking staff Model paper 6

∠IRE = 60° (Each angle of equilateral triangle)
∠RIK = 90°/2 = 45° (As each angle of a square is 90° and the diagonals of the square bisect its angle into two equal parts)
∴ ∠IOR = 180° - (45° + 60°) = 75°