Answer:
[-5, 4) ∪ (4, ∞)
Step-by-step explanation:
Given functions:


Composite function:
![\begin{aligned}(f\:o\:g)(x)&=f[g(x)]\\ & =\dfrac{1}{\sqrt{x+5}-3} \end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%28f%5C%3Ao%5C%3Ag%29%28x%29%26%3Df%5Bg%28x%29%5D%5C%5C%20%26%20%3D%5Cdfrac%7B1%7D%7B%5Csqrt%7Bx%2B5%7D-3%7D%20%5Cend%7Baligned%7D)
Domain: input values (x-values)
For
to be defined:


Therefore,
and 
⇒ [-5, 4) ∪ (4, ∞)
Answer:
84.5 m
Step-by-step explanation:
It is often helpful to draw a diagram for word problems involving geometric relationships. One for this problem is shown below.
The mnemonic SOH CAH TOA reminds you of the relationship between sides of a right triangle:
Tan = Opposite/Adjacent
Here we're given angles of depression measured from the horizontal (as shown in the diagram), but it is more convenient to use angles measured from the vertical. In particular, ∠BAO is the complement of 60°, and its tangent is the ratio OB/OA:
tan(30°) = OB/OA
OB = (200 m)·tan(30°) ≈ 115.47 m . . . . . . multiply by OA, use OA=200 m
Likewise, we have ...
OC = (200 m)·tan(45°) = 200 m
Then the width of the river is the difference between these values:
BC = OC -OB = 200 m - 115.47 m = 84.53 m