Which of the following expressions are equivalent to − -e/-f

What are correct trigonometric ratios that could be used to determine the length of ln

41/2 - 1 1/3 what is the answer as a fraction?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is