Answer:
The common difference would be calculated as:
(a21-a19)/2
(-164--(-58 ))/2 (Replacing the values )
(-164 +58)/2 (Changing signs)
(-106)/2(Subtracting)
-53
Then we are going to replace the common difference(d) in the sequence formal with the 21st term . It is done for finding the first term of the sequence.
a21=a0+d*(n-1)
-164=a0+-53*(21-1) (Replacing the values)
-164=a1-53(20) (Subtracting)
-164=a1-1060 (Multiplying )
-164+1060=a1 (Adding 1060 on both sides of the equation)
896=a1
The answer would be : an= 896-53*(n-1), which is the option B.
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Imagine that we cut the cone in half with a vertical plane. In this plane we'd see points a, b and c. We need to find the measure of angle bca, and then double that angle, to obtain the answer to this problem.
Note that tan (angle bca) = opp / adj = 2 / 6, or 1/3, or 0.333...
Working backwards to find angle bca, we use the inverse tangent function:
arctan 0.3333.. = approx. 0.322 radians, or 18.435 degrees.
Doubling that gives us the measurement of the angle formed between the line segments: 2(18.435 deg) = 36.9 degrees, approximately.
Answer:
360
Step-by-step explanation:
The sum exterior angles of any number of side polygon is always 360
