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About Lesson

12.4 Angle Between Two Lines 两条直线的夹角

(1)
If A(0, 1) and B(4, 3), find the equation of the line passing through B, making 45 with AB and cut the y-axis at the negative part.
If this line cut the x-axis at C, find the area of ABC.

##### Answer :
y = 3x – 9，5
(2)
Given that the equation of the hypotenuse of an isosceles right angle triangle is 3x – y + 1 = 0, the coordinate of the right angle is (6, 1), find the equations of the other two sides.

##### Answer :
y = -2x + 13 , y = x – 2
(3)
In an isosceles ABC, AB = AC also the equation of AB and BC are 2x – y + 2 = 0 and x + y + 1 = 0 respectively. The line AC passes through the point (4, 0), find the equation of AC.

##### Answer :
y = x – 2
(4)
In an equilateral ABC, A(2, 3) and equation BC is x + y = 0. Find the equations of the other two sides.

##### Answer :
(5)
If y = 3x is the equation of the mirror that reflected the incident ray x + y = 8, find the equation of the reflection ray.

x – 7y + 40 = 0