In triangle ABC, angle ACB = 90 degrees, PA ⊥ plane ABC, PA = 2, ab = 4, AC = 2 √ 3 Find: 1. The size of dihedral angle p-ac-b 2. The size of dihedral angle a-bc-p If drawing is not convenient, just write the letters of line and face clearly

In triangle ABC, angle ACB = 90 degrees, PA ⊥ plane ABC, PA = 2, ab = 4, AC = 2 √ 3 Find: 1. The size of dihedral angle p-ac-b 2. The size of dihedral angle a-bc-p If drawing is not convenient, just write the letters of line and face clearly

In the triangle ABC, the angle ACB = 90 degrees, ab = 4, AC = 2 √ 3
BC=2
Pan PA to p'c
Then p'c = 2 and vertical AC, BC
P'C＝BC＝2
therefore
Dihedral angle p-ac-b = 45 degrees
Connect PC
PC is vertical
So the angle PCA is the dihedral angle a-bc-p
From PA = 2 AC = 2 root sign 3
So the dihedral angle is 30 degrees

Let f (x) = AX2 + BX + C (a ≠ 0). If the image of F (x + 1) and f (x) is symmetric about y axis, it is proved that f (x + 12) is even function

If f (x + 1) = f (- x), i.e. f (X-12 + 1) = f [- (X-12)], then f (x + 12) = f (- x + 12), then f (x + 12) is even

In the rectangular coordinate system xoy, the left focus f passing through the hyperbola x2a2 − y2b2 = 1 (a > 0, b > 0) is a tangent of circle x2 + y2 = A2 (the tangent point is t), and the hyperbola is right supported at point P. if M is the midpoint of FP, then | om | - | MT | is equal to ()
A. b-aB. a-bC. a+b2D. a+b

The right focus is F2, PF