Question

find the value of A in this question

Answer 1

you can see your answer

Answer 2

The right answer is :
2tan3Acos3A - tan3A + 1 = 2cos3A
=
2tan3Acos3A - tan3A-2cos3A+1=0
=
tan3A(2c0s3A-1)-1(2cos3A-1)=0
=
(tan3A-1)(2cos3A-1)=0
=
Hence, (tan3A-1)=0 or (2cos3A-1)=0
That is, tan3A=1 or 2cos3A=1
That is, A=n/12 or A=n/9