Annabelle measures the sides of 15 right triangles and, based on her observations, she concludes that for any right triangle the sum of the squares of the two legs is equal to the square of the hypotenuse. Which type of reasoning is Annabelle using?

Annabelle is using  the a measure of central tendency defined as the Mode.

Step-by-step explanation: A measure of central tendency in its simplest definition is a single value or measure that can safely be used to represent all members belonging to an entire set of given data. Hence, as a good illustration, one figure can be used to confidently represent all other ninety nine figures where a set of one hundred figures were given.

The mean, median and mode are commonly accepted measures of central tendency.

The mode is the most frequently occurring value in a given set of data. As such, the modal value is statistically acceptable as a representative of the entire set of values or data.

If Annabelle measures the sides of 15 right triangles and based on her observations, she concludes that for any right  triangle the sum of the squares of the two legs is equal to the square of the hypotenuse, what she has done is taking the most frequently occurring value, and in her experiment, the most frequent of all observed data satisfies the Pythagorean Theorem.

That is why Annabelle can confidently make her assumption.