Which of the following are valid PHP Math functions?

The valid PHP Math functions are sqrt(), floor(), and sin(). These functions are part of the math module in PHP and are used for mathematical calculations. The sqrt() function returns the square root of a number, the floor() function rounds a number down to the nearest integer, and the sin() function returns the sine of a number. It's important to note that the functions str_replace(), explode(), substr(), count(), isset(), unset(), strtoupper(), strtolower(), and ucfirst() are not math functions. Learn more: https://www.php.net/manual/en/ref.math.php