Use the chain rule.
Let u = 25sin²(x), such that dy/dx = dy/du · du/dx


Answer:
3
Step-by-step explanation:
If I've read this correctly, it looks like this.

If that is correct, then the first step is to put the top part of the denominator over 3x
The next part is to flip a three tier fraction. I'm afraid I have to show what happens. My latex is not that strong.
What you get is

This is just about your final answer. You could write it as

Equation of a circle in standard form:
(x-h)²+(y-k)²=r²
r=radius
(h,k) is the center.
In this case:
(h,k) =(0,0) (h=0,k=0 )
r=4
Therefore:
(x-0)²+(y-0)²=4²
x²+y²=16
Answer: x²+y²=16