If sin x = -1, x can be
Since, sin x graph is periodic function with period 2π. So, we shall find the value of x when sin x = -1 in the interval of [0, 2π) and then add or subtract 2π for other values of x.
sin x = -1
x = 270∘
other values of x should be 270∘ + 360∘ = 630∘
and
270∘ + 720∘ = 990∘
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If we take angles in clockwise direction
sin x = -1
x = −90∘
for other angles subtract −360∘ from previous angle
x = -90 - 360∘ = −450∘
x = -450 - 360∘ = −810∘
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So, all A, B, C, D options are correct.