If A(2)=15 & A(15)=80 find explicit equation

What basic trigonometric identity would you use to verify that csc x sec x cot x = csc^(2)x

Answer pls man im trying to get out of summer school

The ideal weight of a nickel is 0.176 ounce. to check that there are 40 nickels in a roll, a bank weighs the roll and allows for an error of 0.015 ounce in total weight