Question

How do you calculate arcsin(-0.9871)?

Answer 1

Find arcsin (-0.9871)

Ans: `-80^@79 and -99^@21`

Explanation:

By calculator-->
sin x = -0.9871 --> arc `x = -80^@79`
Trig unit circle gives another arc `x = - 99^@21` that has the same sine value.
If you want the answers by the opposite direction of rotation, then the 2 answers are:
x = 180 + 80.79 = `260^@79` and
x = 180 + 99.21 = `279^@21`

Check by calculator
sin (260.79) = -0.9871. OK
sin (279.21) = - 0.9871. OK