Let us consider a point (longitude, latitude) on Earth (location).
How to construct a square grid around this point (taking this point as the centre of the square or intercept of the two diagonals) with size of the square as 0.1 degree times 0.1 degree and direction of the one side of square is theta degree?
For example, let the sample point to be (88.38045, 21.04247) and theta = 70 degree. Here is a rough plot for clarification.
Note: This direction is computed from the 84 E meridian.