If a current 0.4A flow for 2 second find the quantity of electricity tranform

Determine the expected diffraction angle for the first-order reflection from the (310) set of planes for bcc chromium when monochromatic radiation of wavelength 0.0735 nm is used. the atomic radius for cr is 0.1249 nm.

Explain vector addition, triangle method and parallelogram method

Could someone . i have tried to solve myself but my calculation is off