Solution:
With reference to Fig. 1
Let 'x' be the distance from the wall
Then for DAC:
⇒
Now for the BAC:
⇒
Now, differentiating w.r.t x:
For maximum angle, = 0
Now,
0 = [/tex]\frac{d}{dx}[tan^{-1} \frac{d + h}{x} - tan^{-1} \frac{d}{x}][/tex]
0 =
After solving the above eqn, we get
x =
The observer should stand at a distance equal to x =
T<u>he direction of motion</u> of the person relative to the water is <u>16.7° north of east.</u>
Why?
We can solve the problem by applying the Pitagorean Theorem, where the first speed (to the north) and the second speed (to the east) corresponds to two legs of the right triangle formed with them. (north and east directions are perpendicular each other)
We can calculate the angle that give the direction using the following formula:
Now, substituting the given information we have:
Hence, we have that <u>the direction of motion</u> of the person relative to the water is 16.7° north of east.
Have a nice day!