Final answer:
To find the point where the lifeguard should stop running and start swimming to reach the drowning swimmer fastest, we need to determine the time it takes for the lifeguard to reach the swimmer by running and swimming.
Step-by-step explanation:
To find the point where the lifeguard should stop running and start swimming to reach the drowning swimmer fastest, we need to determine the time it takes for the lifeguard to reach the swimmer by running and swimming.
Let the distance between the point Q and the lifeguard be x.
Using the distance formula, we can create two equations:
Equation 1: x^2 + 28^2 = 82^2
Equation 2: x/8 + (82-x)/5 = t
Solving these equations will give us the value of x, which represents the distance from point Q where the lifeguard should stop running and start swimming.