help please explain cleary its due in a hour

Question

~Solve  5 cos ( 2 t ) = 5 sin ^ 2 ( t ) + 1 for all solutions  0≤ t <2π t =     Give your answers accurate to at least 2 decimal places, as a list separated by commas

Answer 1

5 cos (2t) = 5 sin² (t) + 1

5(1 - 2 sin² (t)) = 5 sin² (t) + 1 Double angle formula

5 - 10 sin² (t) = 5 sin² (t) + 1

4 = 15 sin² (t)

4 / 15 = sin² (t)

±2√15 / 15 = sin (t)