It'd be easier to do #18 if y ou were to break it up:
14* (first term + 14th term)
Sum from n=1 to 14 of n = S = ---------------------------------
14 2
14(1+14)
= ---------------- = 7(15) = 105
2
The sum of twice that is 210. The sum of "1 from n=1 to n=14" is just 14.
The final sum is 210 + 14 = 224 (answer)
Answer:
11.33 in. to the nearest hundredth.
Step-by-step explanation:
The perimeter of the shaded area = length of the 2 straight lines + the length of the 2 arcs = 4 + length of the 2 arcs.
Calculate the length of the outer arc:
This equals (30 / 360) * perimeter of the largest circle
= 1/12 * 2 π * 8
= 4/3 π in.
The inner circle has a radius of 8 - 2 = 6 ins
so the length of the inner arc
= 1/12 * π * 2 * 6
= π in.
So the perimeter of the shaded region = 4 + 4/3 π + π
= 4 + 7π/3
= 11.33 in.
Answer:

Step-by-step explanation:

The answer to number 17 is c