Maths-
General
Easy
Question
If a, b, c are non-coplanar unit vectors such that a × (b × c) = 
, then the angle between a and b is -
- 3/4
- /4
- /2
-
The correct answer is: 3/4
The given equality implies
(a . c) b – (a . b) c =
b = 
c
b and c are collinear thus a, b, c are coplanar if a . c 
and a . b – . Hence a . b = – cos = –1/
, where is the angle between a and b. So = 3/4.
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