<?php
function
angle_triangle(
$x1
,
$x2
,
$x3
,
$y1
,
$y2
,
$y3
,
$z1
,
$z2
,
$z3
)
{
$num
= (
$x2
-
$x1
) * (
$x3
-
$x1
) +
(
$y2
-
$y1
) * (
$y3
-
$y1
) +
(
$z2
-
$z1
) * (
$z3
-
$z1
);
$den
= sqrt(pow((
$x2
-
$x1
), 2) +
pow((
$y2
-
$y1
), 2) +
pow((
$z2
-
$z1
), 2)) *
sqrt(pow((
$x3
-
$x1
), 2) +
pow((
$y3
-
$y1
), 2) +
pow((
$z3
-
$z1
), 2));
$angle
=
acos
(
$num
/
$den
) *
(180.0 / 3.141592653589793238463);
return
$angle
;
}
$x1
= -1;
$y1
= 3;
$z1
= 2;
$x2
= 2;
$y2
= 3;
$z2
= 5;
$x3
= 3;
$y3
= 5;
$z3
= -2;
$angle_A
= angle_triangle(
$x1
,
$x2
,
$x3
,
$y1
,
$y2
,
$y3
,
$z1
,
$z2
,
$z3
);
$angle_B
= angle_triangle(
$x2
,
$x3
,
$x1
,
$y2
,
$y3
,
$y1
,
$z2
,
$z3
,
$z1
);
$angle_C
= angle_triangle(
$x3
,
$x2
,
$x1
,
$y3
,
$y2
,
$y1
,
$z3
,
$z2
,
$z1
);
echo
"Angles are :\n"
;
echo
"angle A = "
.
round
(
$angle_A
, 3) .
" degree\n"
;
echo
"angle B = "
.
round
(
$angle_B
, 3) .
" degree\n"
;
echo
"angle C = "
.
round
(
$angle_C
, 3) .
" degree\n"
;
?>