A bar graph is when you want to compare the data in the data set (which this data set does)
A line graph is used when the data set creates a straight line (which this data set does not)
A circle graph (also known as a pie chart) is used when the data set measures percentages that will total 100% (which this data set does not)
A stem plot is used when you want to show the frequency of the beginning digit <em>or digits</em> (which this data set does not)
Answer: A
The answer to your question is option b

Length of each side of each of these three equilateral triangle is :
Solution is in attachment ~