Question #79779

1 Answer
Mar 8, 2016

sin(3theta)=sin(2theta+theta)=sin2thetacos theta+cos2theta sintheta
cos(3theta)=cos(2theta+theta)=cos(2theta)costheta-sin(2thetasintheta)
tan(3theta)=tan(2theta+theta)=(tan(2theta)+tantheta)/(1-tan(2theta)(tantheta))

Explanation:

sin(3theta)=sin(2theta+theta)=sin2thetacos theta+cos2theta sintheta
cos(3theta)=cos(2theta+theta)=cos(2theta)costheta-sin(2thetasintheta)
tan(3theta)=tan(2theta+theta)=(tan(2theta)+tantheta)/(1-tan(2theta)(tantheta))
Note you can simplify the double angles by using the appropriate double angle formula to dissolve it