Answer:
Domain : 0° < x <90°
Range: 90° < y < 180°.
Step-by-step explanation:
When we have a function:
f(x) = y
the domain is the set of the possible values of x, and the range is the set of the possible values of y.
In this case we have:
x + y = 180°
such that x < y
Let's analyze the possible values of x.
The smallest possible value of x must be larger than 0°, as we are workin with suplementary angles.
Knowing this, we can find the maximum value for y:
0° + y = 180°
y = 180° is the maximum of the range.
Then we have:
0° < x
y < 180°
To find the other extreme, we can use the other relation:
x < y.
Then, we can impose that x = y (this value will not be either in the range nor the domain)
if x = y then:
x + y = x + x = 180
2*x = 180
x = 90°
This will be the maximum of the domain and the minimum of the range.
Then we have that the domain is:
0° < x <90°
And the range is:
90° < y < 180°.
Taking the square root of both sides gives two possible cases,
or
Recall that
If 
and 
, we have
so in the equations above, we can write
Then in the first case,
(where 
is any integer)
and in the second,
Then the solutions that fall in the interval 
are
How much dose it cost per pound?
Answer:
C. The sum of 18 and half the product of 9 and 4.
