On a dark night, two ships, Saga and Hero, sail parallel to a straight coastline on which there are two lights of equal brightness, 16 kilometres apart. P(x, b) b (-8, 0) (8, 0) x

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter4: Polynomial And Rational Functions
Section4.6: Variation
Problem 7E
icon
Related questions
Question
On a dark night, two ships, Saga and Hero, sail parallel to a straight coastline on
which there are two lights of equal brightness, 16 kilometres apart.
P(x, b)
(-8, 0)
(8, 0) x
Suppose the coastline is represented by the x axis where the origin O is chosen
to be the midpoint of the light sources. It is known that the (total) brightness
from the lights on a ship at point P(x, b) is
1
I =
b² +(x+8)² 'b² +(x-8)²
+
dI
(i) Show that
dx
2P
where
P= (x+8)(3² +(x – 8)*)* +(x -8)(s² +(x + 8)*)* |
and Q = (3° +(x +8)*)} (s? +(x-87)'.
To answer parts (ii) and (iii), you may assume the following factorisation, given
by a computer package, that
P= 2x(x² + 64 + b? +16/64 + b² (x² + 64 + b² –16/64 + b²).
(ii) Saga sails parallel to the coast at a distance 15 km from the coast.
dI
show that, as Saga sails from left to right, the brightness
By considering
on Saga increases to a maximum when x= 0 and then decreases.
dx
(iii) Hero sails parallel to the coast at a distance 6 km from the coast.
Describe how the brightness on Hero changes as Hero sails from left to
right. Give clear reasons for your answer.
Transcribed Image Text:On a dark night, two ships, Saga and Hero, sail parallel to a straight coastline on which there are two lights of equal brightness, 16 kilometres apart. P(x, b) (-8, 0) (8, 0) x Suppose the coastline is represented by the x axis where the origin O is chosen to be the midpoint of the light sources. It is known that the (total) brightness from the lights on a ship at point P(x, b) is 1 I = b² +(x+8)² 'b² +(x-8)² + dI (i) Show that dx 2P where P= (x+8)(3² +(x – 8)*)* +(x -8)(s² +(x + 8)*)* | and Q = (3° +(x +8)*)} (s? +(x-87)'. To answer parts (ii) and (iii), you may assume the following factorisation, given by a computer package, that P= 2x(x² + 64 + b? +16/64 + b² (x² + 64 + b² –16/64 + b²). (ii) Saga sails parallel to the coast at a distance 15 km from the coast. dI show that, as Saga sails from left to right, the brightness By considering on Saga increases to a maximum when x= 0 and then decreases. dx (iii) Hero sails parallel to the coast at a distance 6 km from the coast. Describe how the brightness on Hero changes as Hero sails from left to right. Give clear reasons for your answer.
Expert Solution
steps

Step by step

Solved in 5 steps with 1 images

Blurred answer
Recommended textbooks for you
Algebra & Trigonometry with Analytic Geometry
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:
9781133382119
Author:
Swokowski
Publisher:
Cengage