How would you prove using the cancellation laws 2arccos(x) = arccos(2x² - 1). I am stumped. Any guidance is appreciated.(adsbygoogle = window.adsbygoogle || []).push({});

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Prove Trig Identity

**Physics Forums | Science Articles, Homework Help, Discussion**