Step-by-step explanation:
Given sets are :
A = {1,2,3,4} and B = {a,b,c}
(i)
Step-by-step explanation:
answer is first option,,,
Essentially, you can always tell a thing's position by 3 coordinates. We also say that our world is three-dimentional: it has three dimensions -that's why three coordinates are needed. If something is on a flat surface, you know its one coordinate (all points on the same surface have the same coordinate) so you only need two more (you can call them vertical and horizontal)
The area of the base (six triangles with a base 15m and a height 7.5√3m):

The area of side walls (six triangles with a base 15m and a height 12m)

The surface area:
Remark
The closest answer is D, but the answer has to be rewritten: f(x) = - 2/3 (6)^(x - 1) where x is 1,2,3,4,5,6 .... to plus infinity. If that is not what you are given, there is no answer.
Discussion
The minus sign is misplaced. There are 2 reasons.
1. When x is odd, then the minus sign is not there and every other term will be plus.
2. For a related reason, you cannot get a minus 2/3 if the sign is affected by the power. The first term must be -2/3. (-6)^0 power is 1 not -1
Answer: There is no answer, but you could try C if D does not work.