straight line
2007-12-20 2:03 am
Two lines pass through (4,3) and each line makes an angle 45°with the line y=1/3x. find the equations of the two lines.
回答 (1)
2007-12-20 2:47 am
✔ 最佳答案
設L:y=mx+ctan45°=∣(m-1/3) / [1+m/3] ∣
±1= (3m-1) / (3+m) [[[(右邊分子分母乘3)]]]
3+m=3m-1 or -3-m=3m-1
2m=4 or 4m=-2
m=2 or -1/2
∴y=2x+c and
y=-1/2+c
put(4,3)
3=2(4)+c , 3=-1/2(4)+c
c=-5 , c=5
two lines
y=2x-5
y=-1/2+5
參考: me
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