Answer:
A
Step-by-step explanation:
Lets first solve the relation for "y". Shown below:

This is clearly an equation of a line in the form 
It will be a negatively sloped line, when graphed.
We can use vertical line test to determine function or relation. If a vertical line passes through only 1 point in the graph, we say that it is a function.
Think of a negatively sloped line. No matter where you draw a vertical line, it will only cut the line at 1 point.
So, this is definitely an equation of a function
Correct answer is A
Answer:
b
Step-by-step explanation:
Answer:
x = 180
Step-by-step explanation:
First, you need to know
1. Double-angle formula:
cos(2x) = 
2. Pythagorean identity:

Back to your problem, replacing the variable by the above:

By Double-angle formula
By Pythagorean identity
Given 



, we know -1 < sinx < 1, for every x ∈ R



Answer:
Rational
Step-by-step explanation:
This number is rational because it can be expressed as a ratio between two numbers.
Answer:
50.27
Step-by-step explanation:
area of a circle: pi X r^2
r= radius