Final answer:
A headache located in the forehead for three days, as reported by a patient, is documented by an EMT as a subjective finding, which is based on the patient's own experience and cannot be objectively measured.
Step-by-step explanation:
When an EMT documents a patient's complaint of a headache located in their forehead for three days, this should be recognized and documented as a subjective finding. The term 'subjective' refers to any information provided by the patient about what they are feeling or experiencing, which cannot be objectively measured or verified by the healthcare provider. In contrast to objective symptoms that can be directly observed or measured, such as a fever or an elevated heart rate, subjective findings rely on the patient's personal experience of their illness.