math.asin

local result = math.asin(
    value
)

Type	Name	Description
`number`	value	Sine value in the range [-1, 1]

Type	Name	Description
`number`	result	Arc sine in radians, in the range [-pi/2, pi/2]

Arc sine of 0

local result = math.asin(0)

engine.print("info", result) -- 0.0

Arc sine of 1 is pi/2

local result = math.asin(1)

engine.print("info", result) -- 1.5707963267949

Arc sine of 0.5 is 30 degrees

local result = math.deg(math.asin(0.5))

engine.print("info", result) -- 30.0

Arc sine of -1 is -pi/2

local result = math.asin(-1)

engine.print("info", result) -- -1.5707963267949

Recover angle from a vertical direction component

local dir_y = 0.866 -- sin(60 degrees)
local angle_deg = math.deg(math.asin(dir_y))

engine.print("info", angle_deg) -- 59.999

Verify asin and sin are inverses

local angle = math.pi / 6
local result = math.asin(math.sin(angle))

engine.print("info", result) -- 0.5235987755983