Answer:
c ) A - B is perpendicular to A + B
Explanation:
a ) and b ) Â is not true when A and B are inclined at some angle.
d ) is wrong because A - B can not be perpendicular to B - A when they are linear because each will be equal to zero.
e ) is wrong because magnitude of A+ B will be more than magnitude of
A - B when angle between them is acute.
So c ) option is right .
( A + B ) dot product  ( A - B ) = A² - B² = 0
Hence ( A + B ) is perpendicular to  ( A - B ) .