The diameter is a line that stretches across the middle of a circle from end to end. The radius is one half of this line, stretching from the center of the circle to a point on the side of the circle. This means that the diameter is 2 times the length of the radius. 2 times 2 is 4, meaning that the diameter is 4 inches.
<span>Lets make it clear: You would have a positive answer when the value you are looking for has to be a positive number. On the other hand you would have a positive and a negative answer when you take the square root of something that doesn't have to be positive. it could be either because when a negative number is squared it becomes positive and when a positive number is squared it stays positive as well.</span>