The answer for 4x10^2 would be 400
B would have to equal c in order to get a
So, from the first term, to the fifteen term, there are 14 terms to go through.
that means, if say the common difference is say "d", we have to add "d" 14 times, to get to the 15th term, lemme make a quick table,

and surely you know how much that is.
Answer:
∠ACB = 72
Step-by-step explanation:
OAD is straight line.
∠DAB + ∠OAB = 180
142 + ∠OAB = 180
∠OAB = 180 - 142
∠OAB = 38
ΔAOB is isosceles triangle. OA = OB = radius
∠OAB = ∠OBA = 38 {angles opposite to equal sides or equal}
In ΔAOB ,
∠OAB + ∠OBA + ∠AOB = 180 {Anlge sum property of triangle}
38 + 38 + ∠AOB = 180
76 + ∠AOB = 180
∠AOB = 180 - 76
∠AOB = 104
THe angle subtended by an arc of a circle at the center is double the angle subtended by it at any point on the remaining part of the circle
∠AOB = 2*∠ACB
∠ACB = ∠AOB/2
= 104/2
∠ACB = 72
Answer:
or 
Step-by-step explanation:
or 
