Answer:
The radius of the circle is 
Step-by-step explanation:
we know that
In a circle, a 90-degree sector represents a quarter of the circle area.
The area of a quarter circle is equal to

we have
----> area of a quarter circle
so

Simplify


It’s a!! you can check by replacing x with the numbers inside the brackets until the equality is true!
Difference between two things known as equation and expression.
The answer to the question is 2:3