After nine years, the total was $430. After 12 years, the total amount in Sally's savings account was $480.
1 answer:
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Answer:
The area of the shaded portion of the figure is
Step-by-step explanation:
see the attached figure to better understand the problem
we know that
The shaded area is equal to the area of the square less the area not shaded.
There are 4 "not shaded" regions.
step 1
Find the area of square ABCD
The area of square is equal to
where
b is the length side of the square
we have
substitute
step 2
We can find the area of 2 "not shaded" regions by calculating the area of the square less two semi-circles (one circle):
The area of circle is equal to
The diameter of the circle is equal to the length side of the square
so
---> radius is half the diameter
substitute
Therefore, the area of 2 "not-shaded" regions is:
and the area of 4 "not-shaded" regions is:
step 3
Find the area of the shaded region
Remember that the area of the shaded region is the area of the square less 4 "not shaded" regions:
so
---> exact value
assume
substitute
