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不難maTHS第2回
in the following figure ABCDEFGH is a cube . W,XnadY are the mid-pont of AF,BGand DE respectively. http://www.wretch.cc/album/show.php?i=ming21ki&b=1&f=1862924197&p=2 A.三角形ACW B.三角形BCW C.三角形WCY D.三角形XCW 更新: =.=MC題 更新 2: 死啦....打小左=.=.==.=對不起,真的sorry阿...嗚嗚嗚嗚嗚嗚嗚 which of the following is the angle between the line segment WC and the plane BCHG?
最佳解答:
你的問題是否求這四個三個形的面積？ 設正立方體的邊長是 a 圖片參考：http://hk.geocities.com/namsm4e/P98.jpg A.三角形ACW AC = a√2 AW = a/2 ΔACW = (1/2)ACxAW = (1/2)(a√2)(a/2) = a2√2 / 4 B.三角形BCW BC = a BW = √(a2 + (a/2)2) = √(5a2/4) = a√5 / 2 ΔBCW = (1/2)BCxBW = (1/2)(a)( a√5/2) = a2√5/4 C.三角形WCY WY = a YC = BW = a√5 / 2 ΔWCY = (1/2)YCxYW = (1/2)( a√5/2)(a) = a2√5/4 D.三角形XCW WX = a XC = BW = a√5 / 2 ΔXCW = (1/2)XCxXW = (1/2)( a√5/2)(a) = a2√5/4 A(ΔACW) 的面積和其它 B(ΔBCW)、C(ΔWCY)、D(ΔXCW) 不同
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不難maTHS第2回
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發問:in the following figure ABCDEFGH is a cube . W,XnadY are the mid-pont of AF,BGand DE respectively. http://www.wretch.cc/album/show.php?i=ming21ki&b=1&f=1862924197&p=2 A.三角形ACW B.三角形BCW C.三角形WCY D.三角形XCW 更新: =.=MC題 更新 2: 死啦....打小左=.=.==.=對不起,真的sorry阿...嗚嗚嗚嗚嗚嗚嗚 which of the following is the angle between the line segment WC and the plane BCHG?
最佳解答:
你的問題是否求這四個三個形的面積？ 設正立方體的邊長是 a 圖片參考：http://hk.geocities.com/namsm4e/P98.jpg A.三角形ACW AC = a√2 AW = a/2 ΔACW = (1/2)ACxAW = (1/2)(a√2)(a/2) = a2√2 / 4 B.三角形BCW BC = a BW = √(a2 + (a/2)2) = √(5a2/4) = a√5 / 2 ΔBCW = (1/2)BCxBW = (1/2)(a)( a√5/2) = a2√5/4 C.三角形WCY WY = a YC = BW = a√5 / 2 ΔWCY = (1/2)YCxYW = (1/2)( a√5/2)(a) = a2√5/4 D.三角形XCW WX = a XC = BW = a√5 / 2 ΔXCW = (1/2)XCxXW = (1/2)( a√5/2)(a) = a2√5/4 A(ΔACW) 的面積和其它 B(ΔBCW)、C(ΔWCY)、D(ΔXCW) 不同
其他解答:
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