Given A(1,3) , B(2,7),C(5,3) and D(2,1).Consider the lines : AB,AC,AD,BC,BD,CD
a .Which line is horizontal
b .Which line is vertical
Arrange the lines,except the one in (b), in the ascending order of their steepnesses.Show steps
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Find the value of x if the slope of PQ is-2 where P is (x,3) and Q is (5,9)
再來數學問題 10分
2008-02-25 2:44 am
回答 (2)
2008-02-27 5:05 am
✔ 最佳答案
a. Which line is horizontal: Line AC as y-coordinate are sameSlope AC= (y2-y1)/(x2-x1) = (3-3)/(5-1) = 0
b. Which line is vertical: Line BD as x-coordinate are same
Slope BD= (y2-y1)/(x2-x1) = (7-1)/(2-2) = infinity
Slope AB= (7-3)/(2-1) = +4
Slope AD= (1-3)/(2-1) = -2
Slope BC= (3-7)/(5-2) = -4/3
Slope CD= (1-3)/(2-5) = -2/3
-2 < -4/3 < -2/3 < 0 < +4
Therefore,
slope AD < BC < CD < AC < AB.
Slope PQ = (9-3)/(5-x) = -2
6/(5-x) = -2
-3 = 5-x
x = 8
2008-02-27 8:57 pm
a. we can see that from the y-intecept, if the same, then it must be horizontal
b.we can see that from the x-intecept, if the same, then it must be vertical
b.we can see that from the x-intecept, if the same, then it must be vertical
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