Answer:
The first term is:
Step-by-step explanation:
The arithmetic sequence is defined by
where
is the first term
is the common difference
as
the 17th term of an arithmetic sequence is 51.
i.e.
so
∵
,
,
∵
Therefore, the first term is:
The area of the shaded region = 330 sq cm
Step-by-step explanation:
Given,
The radius of small circle (r) = 4 cm
The radius of large circle (R) = 11 cm
To find the shaded region
Formula
The area of circle of radius r = π sq cm
So, The radius of the small circle = π× sq cm = 16π sq cm
The radius of the large circle = π× sq cm = 121π sq cm
Hence the area of the shaded region = 121π-16π sq cm
= 105π sq cm
= 105 × sq cm = 330 sq cm