急~數學簡單~(10點)~快~快!!!－香港介紹ppt

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急~數學簡單~(10點)~快~快!!!

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1. A man walks 15km east. Then he walks 36km north. How Far is he from his original position?2. If the radius of the circle is 5cm and D is the mid-point of the chord AB;DE=2cm,the length of AB is.圖片參考：http://imgcld.yimg.com/8/n/HA07231216/o/701104050104013873407820.jpg 7. PQRS is a square. T... 顯示更多 1. A man walks 15km east. Then he walks 36km north. How Far is he from his original position? 2. If the radius of the circle is 5cm and D is the mid-point of the chord AB;DE=2cm,the length of AB is. 圖片參考：http://imgcld.yimg.com/8/n/HA07231216/o/701104050104013873407820.jpg 7. PQRS is a square. T is a point on PQ. IF SR=12cm, TQ=7cm,then ST=? 圖片參考：http://imgcld.yimg.com/8/n/HA07231216/o/701104050104013873407831.jpg

最佳解答:

1) Let the distance be x, 152+362= x2 (Pyth. thereom) 225+1296= x2 1521=x2 39km=x 2) OE=OD+DE 5=OD+2 OD=3 Draw a line OB such that OB=5cm OB2=OE2+DB2 52=32+DE2 25=9+DE2 16=DE2 DE=4 7)Draw a line XT so that XT is perpendicular to SR SR=TQ SR=TQ+XS XS=5cm SX2+XT2= ST2 (Pyth. thereom) 52+122=ST2 25+144=ST2 169=ST2 13cm=ST P.S. 2=平方

其他解答:

Q1. Let the distance be x, 15^2+36^2=x^2 x=39 The distance is 39km. Q2. OA=5cm , DE=2cm. AD^2=5^2-(5-2)^2 AD^2=16 AD=4 AB=2AD=8cm Q7. ST^2=SP^2+(PQ+TQ)^2 ST^2=12^2+(12-7)^2 ST^2=169 ST=13 ST=13cm