Contact us
Choose a category below so we can get back to you as quickly as possible.
都不對. 1、cos3a=cos(2a+a)=cos2acoa-sin2asina; 2、與上題類似,此題結果也是錯的.
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.