What characteristic of a triangle is measured when finding the area using two sides and the included angle?

When calculating the area of a triangle using two sides and the included angle, the specific characteristic being measured is the angle formed between those two sides, which can indeed be referred to as an oblique angle. This is relevant because the formula for the area of a triangle with two sides and the included angle is given by:

Area = 1/2 * a * b * sin(C)

where "a" and "b" are the lengths of the two sides, and "C" is the measure of the included angle. An oblique triangle is one that does not contain a right angle, meaning it could be either acute or obtuse.

While acute angles and obtuse angles can be included in the calculation, the terminology of "oblique angle" encompasses both cases where the angle is either less than or greater than 90 degrees but excludes right angles. Therefore, the best descriptor for the type of angle measured in this context is indeed an oblique angle. This focus highlights an important aspect of triangle geometry and area calculation.