三角形ABC中,C=2B,三邊記為a,b,c,則sin3B/sinB等于( )A.b/aB.a/bC.c/aD.a/c請(qǐng)寫出步驟.謝謝!

熱心網(wǎng)友

選B。A=180-C-B=180-3B，sinA=sin3Bsin3B/sinB=sinA/sinB=a/b.