If a straight line is drawn through the point P (1,2) and its inclination angle is twice that of the straight line L: x-y-3 = 0, then the equation of the straight line is______ ．

If a straight line is drawn through the point P (1,2) and its inclination angle is twice that of the straight line L: x-y-3 = 0, then the equation of the straight line is______ ．

Let the inclination angle of the straight line l be α and α ∈ (0, π 2) ∪ (π 2, π). First, according to x-y-3 = 0, the slope of the straight line is 1, and according to the slope k = Tan α = 1, α = 45 degrees. Because the inclination angle of the straight line is 2 α = 90 degrees, the straight line is perpendicular to the X axis and passes (1, 2), so the equation of the straight line is x = 1, so the answer is x = 1

If a straight line is drawn through the point P (1,2) and its inclination angle is twice that of the straight line L: x-y-3 = 0, then the equation of the straight line is______ ．

Let the inclination angle of the straight line l be α and α ∈ (0, π 2) ∪ (π 2, π). First, according to x-y-3 = 0, the slope of the straight line is 1, and according to the slope k = Tan α = 1, α = 45 degrees. Because the inclination angle of the straight line is 2 α = 90 degrees, the straight line is perpendicular to the X axis and passes (1, 2), so the equation of the straight line is x = 1, so the answer is x = 1

The line L passing through the point m (1.2) divides the graph C: (X-2) * 2 + y * 2 = 9. D into two arcs?
(X-2) * 2 + y * 2 = 9 * 2 is the square

Center P (2,0)
The slope of PM = (0-2) / (2-1) = - 2
The line should be perpendicular to PM, so its slope = - 1 / 2
Linear equation: Y-2 = (- 1 / 2) (x-1)
y=(-1/2)x+(5/2)