Answer:
Fragment shader:
The fragment shader is the process in which a fragment shader basically generated by rasterization into the set of pixels, colors and single depth number.
It is also known as pixel shader where each pixel sample are basically cover by the primitive that generated fragment.
Tri-linear filtering:
Trilinear filtering is the extra filtering image that basically improve the quality of the image. It also perform linear interpolation in the mipmaps. Trilinear filtering is the extension of bi-linear filtering method that is basically required for polygon in the pixel.