The first term of this series (a+1) is 1 and the common ratio (r) is -3.
Thus, the explicit formula is a_n = 1*(-3)^(n-1).
Must check this! suppose we try to calculate the 3rd term. Then n = 3.
a_3 = 1*(-3)^(3-1) = (-3)^2 = 9. This is correct.
Supplement is 180- angle
180-95 = 85
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