Question

Repost question: Guys, can you please help me write an expression for shaded area circle and please expand and simplify for me, guys, please? :)

Answer 1

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!!

(also, you don't have to, but marking brainliest gives you some of your points back anyway)

Answer 2

Step-by-step explanation:

area of shaded area = area of larger circle - area of smaller circle

a = pi * (r+7)^2 - pi * r^2

a = pi * r^2 + 14pi*r + 49* pi - pi * r^2

pi r^2 cancels

a = 14*pi*r + 49 *pi

a = 7pi(2r + 7)