www.fltk.net > 已知AB均为钝角且sinA=根号5/5,sinB=根号10/10,...

已知AB均为钝角且sinA=根号5/5,sinB=根号10/10,...

因为A,B为钝角,所以: cosA=-2√5/5,cosB=-3√10/10. 则: sin(A+B) =sinAcosB+cosAsinB =(√5/5)*(-3√10/10)+(-2√5/5)*(√10/10) =-3√50/50-2√50/50 =-√50/10 =-√2/2. 即:A+B=225°

A,B均为钝角且sinA=根号5/5,则cosA=-根号(1-sinA^2)=-2根号5/5,sinB=根号10/10cosB=-根号(1-sinB^2)=-3根号10/10cos(A+B)=cosAcosB-sinAsinB=(-2根号5/5)*(-3根号10/10)-(根号5/5)*(根号10/10)=6*5根号2/50-5根号2/50=25根号2/50=根号2/2A,B均...

网站地图

All rights reserved Powered by www.fltk.net

copyright ©right 2010-2021。
www.fltk.net内容来自网络,如有侵犯请联系客服。zhit325@qq.com