Answer
The first five terms are $3\pi-2,2\pi-1, \pi,1, 2-\pi$
Work Step by Step
As we know that the common difference of an arithmetic sequence can be written as:
$$d=a_{n+1}-a_n$$
The next term of an arithmetic sequence can be computed by adding the common difference $d$ to the previous term, thus:
$$ a_{n+1}=a_{n}+d$$
We were given $a_4=1$ (the fourth term) and $a_e=\pi$ (the third term).
Thus,
$$d=a_4-a_3=1-\pi$$
Thus, we can find $a_1, a_2, \text{ and } a_5$ as follows:
$a_5=a_4+d=1+(1-\pi)=2-\pi \\$
$a_3=a_2+d \\
a_2=a_3-d\\
a_2=\pi-(1-\pi)\\
a_2=\pi-\pi\\
a_2=2\pi-1$
$a_1=a_2-d\\
a_1=2\pi-1-(1-\pi)\\
a_1= 2\pi-1-1+\pi\\
a_1=3\pi-2$
Hence, the first five terms are: $3\pi-2,2\pi-1, \pi,1, 2-\pi$
