In a figure , y=kx(k>0) is a straisht line with points B and E lying on it. ABCD and DEFG are two squares each with one side lying on the x-axis.
1. If the coordinatef of A are (2,0), find the coordinates of D in terms of k.
2. Hence find the value of k if the area of the square DEFG is 225/4 square units.
3. Find the coordinates of F.
F.4 Quadratic Equation
2007-10-27 7:25 am
回答 (1)
2007-10-27 8:03 am
✔ 最佳答案
1) y=kx......(*)sub x=2 into (*)
y=2k
AB=2k
D must be a point lies on x-axis (?,0)
as ABCD is a square, so AB = AD
so AD=2k
the coordinate of D is (2k,0)
2)
the length of the side of square DEFG= √(225/4) = 15/2 units
at point E, y=15/2 and x=2k as E is the point just above D
Sub (2k,15/2) into (*)
15/2= k(2k)
15/4=k^2
k=√15/2 or -√15/2
3)
the coordinate of F=(2k+15/2,0) or (2k+15/2,15/2)
=(√15+15/2,0) or (√15+15/2,15/2) (depend F is on x-axis or not)
參考: myself
收錄日期: 2021-04-20 12:03:37
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