Question

If cos^4 A-sin^4 A = 1/2 ,Then A=

Answer 1

Answer is given in the pic.

Answer 2

Step-by-step explanation:

$({ \cos}^{2} a) ^{2} -( { \sin}^{2} a)^{2} = 1 /2 \\( { \cos}^{2} a + { \sin}^{2} a)( { \cos }^{2} a - { \sin }^{2} a) = 1/2 \\ (1)(1- { \sin }^{2} a - { \sin }^{2} a) = 1 /2\\ { 1-2\sin }^{2} a = 1/2 \\ 2{ \sin}^{2} a = 1/2\\ { \sin}^{2} a = 4\\ sin a = 1/2\\ \a = 30 degree$