If cos A=sin2A. and a sin12A+b sin10A+c sin8A+sin6A=1. Then a+b+c=?

If cos A=sin2A. and a sin12A+b sin10A+c sin8A+sin6A=1. Then a+b+c=?

If cos A=sin2A. and a sin12A+b sin10A+c sin8A+sin6A=1. Then a+b+c=?

a)            5

b)            7

c)            6

d)            8

Sol:

quantitative aptitude
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