Final answer:
The heart rate can be determined from a regular ECG tracing by measuring the distance between the R waves and counting the number of R waves within a specific time interval.
Step-by-step explanation:
The heart rate can be determined from a regular ECG tracing by measuring the distance between the R waves. The R wave represents the depolarization of the ventricles, which corresponds to a heartbeat. To calculate the heart rate, count the number of R waves within a specific time interval, usually one minute. This number represents the beats per minute, which is the heart rate.
For example, if there are 10 R waves within a one-minute interval, then the heart rate would be 10 beats per minute.