# ASIN()

### ASIN()

Arcus sine of the argument

Syntax

`      ASIN( nSine ) -> nRadiant`

Arguments

<nSine> the sine of an angle

Returns

<nRadiant> the angle whose sine is <nSine>

Description

The function ASIN() is the inverse function of SIN(). It takes a sine value and returns the smallest(!) angle whose sine equals to the argument. The return value is given in radiants (full angle equals 2*Pi – see DTOR() if you need to convert it into degress). Note, that <nSine> must be between -1 and 1 and that <nRadiant> is always between -PI()/2 and PI()/2.

Examples

```      ? asin( 0.0 ) // --> 0.0
? asin( 0.5 ) // --> 0.5235...```

Tests

```      asin( 0.0 ) == 0.0
asin( sqrt( 1 / 2 ) ) == PI() / 4
asin( 1.0 ) == PI() / 2
asin( 0.0 ) == 0.0  // and not PI(), since the smallest angle is returned !```

Compliance

ASIN() is compatible with CT3’s ASIN().

Platforms

All

Files

Source is trig.c, library is libct.

Seealso

SIN(), COS(), TAN(), COT(), ACOS(), ATAN(), ATN2(), SINH(), COSH(), TANH(), RTOD(), DTOR(), PI()

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