Question

Angle between 1111 and 112 direction in cubic unit cell

Answer 1

cos=ℎ1ℎ2+12+12ℎ21+21+21‾‾‾‾‾‾‾‾‾‾‾‾√ℎ22+22+22‾‾‾‾‾‾‾‾‾‾‾‾√

For the (111) and (121) planes:

cos=1+2+11+1+1‾‾‾‾‾‾‾‾‾√1+4+1‾‾‾‾‾‾‾‾‾√=43‾√6‾√=432‾√

From this,

=19.5°