Answer:
14πr + 49π
Step-by-step explanation:
Logically, to find the area of the border of a circle, we need to find both the area of the inner circle [not including border] and the area of the outer circle [including border]
Once we have found these two areas, we find the difference (difference meaning subtraction) between the two values.
We know that the area of a circle = πr²
We can use this formula to find the area of both circles.
Inner circle:
πr²
(cannot be simplified further)
Outer circle:
π(r + 7)²
(r + 7)² = (r + 7)(r + 7) = r² + 7r +7r +49 {FOIL method}
outer - inner
π(r² + 14r + 49) - πr²
π (r² +14r +49)= πr² + 14πr + 49π
πr² + 14πr + 49π - πr²
πr² - πr² = 0
So, the area of our border is: 14πr + 49π
hope this helps!!
<em>(also, you don't have to, but marking brainliest gives you some of your points back anyway)</em>
