Question

QF Q8.) Use an identity to solve the following equation

Answer 1

11 pi/6 and 0

see photo

*note: it is 11pi/6 not 11pi/12

Answer 2

Using trigo identity cos2x=1-2sin^2x

cos2x=1-2sin^2x=sinx+1

1-2sin^2x=sinx+1

2sin^2x+sinx=0

sinx(2sinx+1)=0

sinx=0 or -1/2

x=0, π, 7π/6, 11π/6