Resposta:
# S = {pi / 6 + 2pin, (5pi) / 6 + 2pin, x = pi / 2 + 2pin} #
Explicació:
Utilitza la propietat Double Argument:
# cos2A = 1-2sin ^ 2A #
# 1-2sin ^ 2x + 3sinx-2 = 0 #
# 2sin ^ 2x-3sinx + 1 = 0 #
# (2sinx-1) (sinx-1) = 0
# 2sinx-1 = 0 o sinx-1 = 0 #
# sinx = 1/2 o sinx = 1
# x = sin ^ -1 (1/2) o x = sin ^ -1 1 #
# x = pi / 6 + 2pin, (5pi) / 6 + 2pin o x = pi / 2 + 2pin
# S = {pi / 6 + 2pin, (5pi) / 6 + 2pin, x = pi / 2 + 2pin} #
