解：a^2=b^2+c^2-2bccosAa^2-c^2=b^2-2bccosA而:b^2=ac,a^2-c^2=ac-bc所以:ac-bc=ac-2bccosAcosA=1/2A=60度而:b/sinB=a/sinAsinB=bsinA/absinB/c=(b^2)sinA/(ac)=sinA=(根号3)/2
