过圆心O作弦AB的垂线OD,
则BD＝12÷2＝6,∠BOD＝60°
∴OB＝BD/sin60°＝6÷√3/2＝4√3
弧长AB＝2×π×4√3×120°/360°＝8√3/3 π.
已知扇形的圆心角是a=120度,弦长AB=12cm,求弧长l
已知扇形的圆心角是a=120度,弦长AB=12cm,求弧长l
数学人气：481 ℃时间：2019-09-24 06:09:02
优质解答
我来回答
类似推荐
猜你喜欢
- 1在△ABC中，已知sinA：sinB：sinC=2：3：4，三角形的周长为18，则△ABC的面积为_．
- 2帮我找找高二英语unit6 life in the future课文
- 3水池有一个注水管和一个排水管,水管注水5分钟注满,放水10分钟放完,注水一段时间后发现底塞未塞,塞上后继续注水,又过了同样多的时间后注满,问一共用了多长时间
- 4More than one student__gone to the USA.A.has B.have C.is D.are
- 52008除以2009分之2007,怎么简算
- 6what is she like ----she is tall and beautiful.此句中 what is she like 能否换成
- 7Much to my delight,when I got back into my office,I found all the lights in it____.
- 8看云识天气第二段的结构方式?
- 9do you have a pen pal?if not.do you want to have one?now let me tell you how to get a pen pal.there are usually three st
- 10扇形的半径不变,圆心角缩小到原来的1/2,面积怎么样?