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Some Maths questions...
1. A bag contains three kinds of coins. Given that no. of $5 coins: no. of $2 coins: no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12]2.In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angleCOB=20degree. Find angleAOD [Ans. 88degree] and the... 顯示更多 1. A bag contains three kinds of coins. Given that no. of $5 coins: no. of $2 coins: no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12] 2.In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angleCOB=20degree. Find angleAOD [Ans. 88degree] and the length of minor arc CD.[Ans:18cm] Thx~ 更新: http://i226.photobucket.com/albums/dd260/wingreally/1.jpg------The diagram of circle
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1. A bag contains three kinds of coins. Given that no. of $5 coins : no. of $2 coins : no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12] Let the no. of $1 coins be x. Then the no. of $2 coins is 2x. The no. of $5 coins is 3x. The amount of $1 coins is $x. The amount of $2 coins is $2 x 2x = $4x The amount of $5 coins is $5 x 3x = 15x x + 4x + 15x = 240 20x = 240 x = 12 The no. of $1 coins is 12. 2. In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angle COB=20 degree. Find angle AOD [Ans. 88 degree] and the length of minor arc CD.[Ans:18cm] angle AOD : angle COB = arc AD : arc BC angle AOD : 20 degree = 22cm : 5cm angle AOD = 22/5 x 20 degree = 88 degree angle AOD + angle DOC + angle COB = 180 degree angle DOC = 180 degree – angle AOD – angle COB = 180 degree – 88 degree – 20 degree = 72 degree arc CD : arc BC = angle DOC : angle COB arc CD : 5cm = 72 degree : 20 degree arc CD = 72/20 x 5cm = 18cm 2009-07-30 01:30:32 補充： In question 1, the $ sign is missing in the following line: The amount of $5 coins is $5 x 3x = $15x 2009-07-30 01:30:45 補充： In question 1, the $ sign is missing in the following line: The amount of $5 coins is $5 x 3x = $15x
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Some Maths questions...
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發問:1. A bag contains three kinds of coins. Given that no. of $5 coins: no. of $2 coins: no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12]2.In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angleCOB=20degree. Find angleAOD [Ans. 88degree] and the... 顯示更多 1. A bag contains three kinds of coins. Given that no. of $5 coins: no. of $2 coins: no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12] 2.In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angleCOB=20degree. Find angleAOD [Ans. 88degree] and the length of minor arc CD.[Ans:18cm] Thx~ 更新: http://i226.photobucket.com/albums/dd260/wingreally/1.jpg------The diagram of circle
最佳解答:
1. A bag contains three kinds of coins. Given that no. of $5 coins : no. of $2 coins : no. of $1 coins=3:2:1 and the total amount of the coins is $240, find the no. of $1 coins. [ Ans: 12] Let the no. of $1 coins be x. Then the no. of $2 coins is 2x. The no. of $5 coins is 3x. The amount of $1 coins is $x. The amount of $2 coins is $2 x 2x = $4x The amount of $5 coins is $5 x 3x = 15x x + 4x + 15x = 240 20x = 240 x = 12 The no. of $1 coins is 12. 2. In the figure, AOB is a diameter, arc BC=5cm, arc AD=22cm and angle COB=20 degree. Find angle AOD [Ans. 88 degree] and the length of minor arc CD.[Ans:18cm] angle AOD : angle COB = arc AD : arc BC angle AOD : 20 degree = 22cm : 5cm angle AOD = 22/5 x 20 degree = 88 degree angle AOD + angle DOC + angle COB = 180 degree angle DOC = 180 degree – angle AOD – angle COB = 180 degree – 88 degree – 20 degree = 72 degree arc CD : arc BC = angle DOC : angle COB arc CD : 5cm = 72 degree : 20 degree arc CD = 72/20 x 5cm = 18cm 2009-07-30 01:30:32 補充： In question 1, the $ sign is missing in the following line: The amount of $5 coins is $5 x 3x = $15x 2009-07-30 01:30:45 補充： In question 1, the $ sign is missing in the following line: The amount of $5 coins is $5 x 3x = $15x
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