Question

角A=60度,c=3b.求a/c的值,

Answer 1

由余弦定理：a^2=b^2+c^2-2bc*cosA

即a^2=(c/3)^2+c^2-2*(c/3)*c*1/2

整理得：a^2=7/9*(c^2)

则：(a/c)^2=7/9

得：a/c=√7/3