I m answering the fourth one....
Please refer the attachment figue to understand better
In triangle BCD
sin # = x/y
So x = ysin#
In trringle ABC
cos # = y/2(root 2)x
cos #= y/2(root 2)ysin#
So 2sin#cos# = 1/root2
sin 2# = 1/root2
# = 45/8
# = 22.5
So the remaining angle is 90-22.5=67.5
Here # = C
Moderation Team
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