Determine the value for the trigonometric expression. give an exact answer in degrees.
hint: consider only the principal value of an inverse trigonometric function.
cos tan

Which expression is equivalent to 2x^2+7x+4?

How can you construct perpendicular lines and prove theorems about perpendicular lines

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.