Question

help me with this question pls.

THe main thing is i don understand the question, when does the bird need to fly across the water? I thought it is always along the shoreline?

Answer 1

Ornithologists have determined that some species of birds tend to avoid °ights over large
bodies of water during daylight hours. It is believed that more energy is required to °y over
water than land because air generally rises over land and falls over water during the day. A
bird with these tendencies is released from an island that is 5 km from the nearest point B
on a straight shoreline, °ies to a point C on the shoreline, and then °ies along the shoreline
to its nesting area D. Assume that the bird instinctively chooses a path that will minimize
its energy expenditure. Points B and D are 13 km apart. If it takes 1.4 times as much energy
to °y over water as land, ¯nd the distance between B and C.

Answer 2

Point A: over water where the bird was let go.
Point B: nearest point on the shoreline.
Point C: first point where the bird is over the shoreline.
Point D: Final place where the bird wanted to go.

Answer 3

this is a calculus (minimization) problem