Contact us
Choose a category below so we can get back to you as quickly as possible.
DC=20聯接AD,由中垂線定理知道BD=AD=10,又因為AB=AC,角BAC=120度,所以角CAD=90度,C=30度,在直角三角形裏,三十度所對的直角邊是斜邊的一半,得出DC是20
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.