91Ó°ÊÓ

Evaluate without using a calculator. $$ \cos \left(\cos ^{-1} \frac{3}{5}\right) $$

In Europe, the voltage of the alternating current coming through an electrical outlet can be modeled by the function \(V=230 \sin (100 \pi t)\), where \(t\) is measured in seconds and \(V\) in volts. What is the frequency of the voltage?

The oscillations in air pressure representing the sound wave for a particular musical tone can be modeled by the equation \(y=0.3 \sin (600 \pi t)\), where \(y\) is the sound pressure in pascals after \(t\) seconds. What is the frequency of the tone?

Evaluate without using a calculator. $$ \sin ^{-1}\left(\sin \frac{\pi}{3}\right) $$

Convert each of the following to radians without using a calculator. \(300^{\circ}\)

Convert each of the following to radians without using a calculator. \(225^{\circ}\)