在PHP中如何执行数学运算？

$a = 10;
$b = 5;

// 加法
$result = $a + $b;
echo "加法结果：" . $result . "<br>";

// 减法
$result = $a - $b;
echo "减法结果：" . $result . "<br>";

// 乘法
$result = $a * $b;
echo "乘法结果：" . $result . "<br>";

// 除法
$result = $a / $b;
echo "除法结果：" . $result . "<br>";

// 取余
$result = $a % $b;
echo "取余结果：" . $result . "<br>";

$num = -10;

// 绝对值
$result = abs($num);
echo "绝对值：" . $result . "<br>";

// 平方根
$result = sqrt($num);
echo "平方根：" . $result . "<br>";

// 取整
$result = ceil($num);
echo "向上取整：" . $result . "<br>";

$result = floor($num);
echo "向下取整：" . $result . "<br>";

// 随机数
$result = rand(1, 100);
echo "生成1到100之间的随机数：" . $result . "<br>";

// 对数
$result = log(10);
echo "自然对数：" . $result . "<br>";

// 三角函数
$result = sin(90);
echo "正弦值：" . $result . "<br>";

$result = cos(0);
echo "余弦值：" . $result . "<br>";

$result = tan(45);
echo "正切值：" . $result . "<br>";