In the parallelogram ABCD, ad = a, be parallel to AC, De, the length line of AC intersects F and be intersects E

In the parallelogram ABCD, ad = a, be parallel to AC, De, the length line of AC intersects F and be intersects E

1. Extend DC to g, cross be to g, ∵ AC ∥ be, ∥ CBE = ∠ BCA = ∠ CAD,
The result is that DC = CG
2. C and F are the median of △ dge, so DF = Fe

If three straight lines l1:4x + y-4 = 0, L2: MX + y = 0, l3:2x-3my-4 = 0 cannot form a triangle, find the value of real number M

Three lines can't form a triangle
1) Three lines meet at one point
2) Any two of the three lines are parallel (or all three lines may be parallel to each other)
And then do it yourself

Known P: x ^ 2-4x + 3

The answers are as follows:
p:x^2-4x+3≤0
(x-1)(x-3)≤0
1≤x≤3
That is, the set of P is {x | 1 ≤ x ≤ 3}
So the set of non-p is {x | x > 3 or X

In p-abc, PAB is perpendicular to ABC, AB is perpendicular to BC, AP is perpendicular to Pb, and PAC is perpendicular to PBC

Because plane PAB is perpendicular to plane ABC
So AP is perpendicular to plane BC
And because AP is perpendicular to Pb
So AP is perpendicular to PBC
Because AP belongs to face PAC,
So PAC is perpendicular to PBC