热心网友
用正弦定理：a/sinA = b/sinB = c/sinC = 2R所以 sinA= a/2R ,sinB= b/2R ,sinC=c/2R代入式子中得：b-c=(3/5)*a
热心网友
利用三角形正弦定理：sinA/a=sinB/b=sinC/c
用正弦定理：a/sinA = b/sinB = c/sinC = 2R所以 sinA= a/2R ,sinB= b/2R ,sinC=c/2R代入式子中得：b-c=(3/5)*a
利用三角形正弦定理：sinA/a=sinB/b=sinC/c