郭敦顒回答:
设公比为r>0且r≠1,则a= a,b= ar,c= ar²,r=b/a.
∵当r>1时a+b>c,∴a+ar >ar²,1+r >r²,r²-r-1<0,
解得r≤1.618;
当r<1时,a<b+c,1<r+r²,解得r≥0619,
∴0.619≤r≤1.618.
按正弦定理,a/sinA=b/sinB,sinB/sinA=b/a=r,
∴sinB/sinA的取值范围为[0.619,1.618]
郭敦顒回答:
设公比为r>0且r≠1,则a= a,b= ar,c= ar²,r=b/a.
∵当r>1时a+b>c,∴a+ar >ar²,1+r >r²,r²-r-1<0,
解得r≤1.618;
当r<1时,a<b+c,1<r+r²,解得r≥0619,
∴0.619≤r≤1.618.
按正弦定理,a/sinA=b/sinB,sinB/sinA=b/a=r,
∴sinB/sinA的取值范围为[0.619,1.618]