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標題:

MATHS f.110分!!!!!!!!!!!!!

發問:

find the area of OAB A(-1 ,3 ) B(-3 ,-2) FIND the area of the quadrilateral ABCD A(-2 .3) B(-3 ,-1) C(-2,-2) D(2,2) given that A(5,3),B(-2,3),C(-2,-2)and D are the vertices of a rectangle ,find the coordinates od D and the area of rectangle ABCD 答案用英文 解釋用中文

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最佳解答:

1. 三角形OAB可用X軸分為兩個三角形，直線AB與X軸於(-2.2,0)相交，可名為C點；兩個三角形為三角形OAC及三角形OBC，以OC為底； Area of triangle OAB (三角形OAB面積) = Area of triangle OAC + area of triangle OBC (三角形OAC面積 + 三角形OBC面積) = [0-(-2.2)](3-0)/2 + [0-(-2.2)][0-(-2)]/2 = (2.2)(3)/2 + (2.2)(2)/2 = 3.3 + 2.2 = 5.5 square units 2. 四邊形ABCD可用AC分為兩個以AC為底的三角形，三角形ABC及三角形ACD； Area of the quadrilateral ABCD (四邊形ABCD面積) = Area of triangle ABC + area of triangle ACD (三角形ABC面積 + 三角形ACD面積) = [3-(-2)][-2-(-3)]/2 + [3-(-2)][2-(-2)]/2 = (5)(1)/2 + (5)(4)/2 = 2.5 + 10 = 12.5 square units 角ABC為直角，由A晝一線AD與線BC平行，由C晝一線CD與線AB平行，兩線在(5,-2)相交； Coordinates of D is (5,-2) Area of rectangle ABCD = [5-(-2)][3(-(-2)] = (7)(5) = 35 square units 2007-09-01 12:41:51 補充： Area of rectangle ABCD= [5-(-2)][3-(-2)]= (7)(5)= 35 square units

其他解答:

1. the area of OAB is 6 2. the area of the quadrilateral ABCD is 13 3. The coordinate od D=(5,-2)and the area of rectangleABCD is 35