acos

(PHP 4, PHP 5)

acos — Oblicza arcus cosinus liczby

Opis

float acos ( float $argument )

Zwraca w radianach arcus cosinus argumentu. Funkcja acos() jest dopełniającą do funkcji cos(), co oznacza, że a==cos(acos(a)) dla każdej wartości z dziedziny funkcji acos().

Parametry

argument: Argument do przetworzenia

Zwracane wartości

Arcus cosinus argumentu w radianach.

Zobacz też:

cos() - Oblicza cosinus kąta
acosh() - Area cosinus hiperboliczny
asin() - Oblicza arcus sinus liczby
atan() - Oblicza arcus tangens liczby

add a note User Contributed Notes acos - [2 notes]

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zoltan dot szentesi at nokia dot com ¶

6 years ago


Wondering what is the use of 'acos' function?



It is essential in games, animations and drawings to determine the location of two objects relating to each other.



To the point: the angle of two vectors is calculated by



           v1X*v2X + v1Y*v2Y

  acos(--------------------------)=angle between two vectors.

               |v1| * |v2|



 |v1| and |v2| are the length of the vectors and calculated using Pithagoras-formula: |v1|=sqrt(v1X*v1X + v1Y*v1Y)



This helped me to calculate and share given space for 'n' amount of objects so that they don't overlap.



Enjoy! :-)

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-2

anthony at interiorgoodsdirect dot com ¶

5 years ago


To calculate an angle from a triangle's sides.



Use the 'law of cosines' :



<?php

//        a²+b²-c²            

// cosC = --------

//           2ab



function calculateAngle($c,$a,$b)

{

    $angleInRadians=acos((pow($a,2) + pow($b,2) - pow($c,2)) / (2 * $a * $b));

    return rad2deg($angleInRadians); 

}

?>



$a, $b, $c are the triangle sides.



The function returns the angle opposite side c, in degrees.

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