In my text, it describes the time it takes for the output to transition from high to low is dependent on the rc time constant of R2 and the gate capacitance as shown in the attached picture. However, there is R3 in the picture that is said to be in parallel with R2, and since R2 is so much smaller than R3, the combo will have a value approximately of R2. Im confused as to why R3 is parallel with R2. Can someone give me some insights. Thanks in advance.