23题第三问用行列式解答
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23. (1) A(1, 2) 在双曲线上,则 m = 2, y = 2/x;
n = 2/(-2) = -1, 2 = k+b, -1 = -2k+b, 联立解得 k = b = 1
y = x+1.
(3). B(3, 4), C(3, 2/3), A(1, 2)
S<△ABC> = (1/2)*
|1 2 1|
|3 2/3 1|
|3 4 1|
= (1/2)*
|1 2 1|
|2 -4/3 0|
|2 2 0|
= (1/2)(4+8/3) = 10/3
n = 2/(-2) = -1, 2 = k+b, -1 = -2k+b, 联立解得 k = b = 1
y = x+1.
(3). B(3, 4), C(3, 2/3), A(1, 2)
S<△ABC> = (1/2)*
|1 2 1|
|3 2/3 1|
|3 4 1|
= (1/2)*
|1 2 1|
|2 -4/3 0|
|2 2 0|
= (1/2)(4+8/3) = 10/3
追问
需要求3点坐标才能行列式?
坐标怎么求的
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