Question

在三角形ABC中,B=4分之π,AC=2倍根号5,CosC=2倍根号5/5

Answer 1

如图：作AE⊥BC交于E,∵ AC=2√5 ,cosC=2√5/5 ,∴ CE=AC*cosC=2√5*(2√5/5)=4 ,∴ AE=√(AC^2-CE^2) =√[(2√5)^2;-(4)^2] =2&...