Two vertical angles are formed. These angles are also equal to each other.
To answer this question we will have to understand the nature of 
.
can be rewritten as: 
. Now, 
is an irrational number and thus any of the four operations of addition, multiplication, subtraction or division placed anywhere between any of these terms will always result in an irrational number.
The only way irrational numbers can be made rational is by dividing or multiplying the given irrational number by the same irrational number.
Answer:
a)
Mean = sum of all numbers in dataset / total number in dataset
Mean = 8130/15 = 542
Median:
The median is also the number that is halfway into the set.
For median, we need to sort the data and then find the middle number which in our case is 546. Below is the sorted data
486 516 523 523 529 534 538 546 548 551 552 558 566 574 586
Standard Deviation (SD). Here X represents dataset and N= count of numbers in data
As per the SD formula, which is Sqrt ( sum (X_i - Meanx(X))/(N-1))
SD= 25.082
2) Formula for coefficient of skewness using Pearson's method (using median) is,
SK = 3* ( Mean (X) - Median(X))/(Standard Deviation) = 3*(542-546)/25.082 = -0.325
3) coefficient of skewness using the software method is also same which is -0.325
