As shown in the figure, in the pyramid p-abcd with rectangular bottom, PA ⊥ plane ABCD, PA = ad, e is the midpoint of PD (1) verification: Pb ∥ plane AEC; (2) verification: plane PDC ⊥ plane AEC

As shown in the figure, in the pyramid p-abcd with rectangular bottom, PA ⊥ plane ABCD, PA = ad, e is the midpoint of PD (1) verification: Pb ∥ plane AEC; (2) verification: plane PDC ⊥ plane AEC

(1) Connect BD to AC at O, connect EO, because o is the midpoint of BD, e is the midpoint of PD, so EO ‖ Pb, (2 points) eo ⊂ plane AEC, Pb ⊄ plane AEC, so Pb ‖ plane AEC; (6 points) (2 points) Pa ⊥ CD, CD ⊂ plane ABCD, so PA ⊥ CD, and ad ⊥ CD, and ad ∩ PA = a

Each face is an equilateral triangle and has four vertices ABCD in the same plane. ABCD is 30cm square
Imagine the structure of geometry and draw its three views and direct view
2 calculate the surface area and volume of the geometry

1, as shown in the figure below; 2, s の = 8 × s △ = 225 √ 3cm & amp; sup2;; & nbsp; & nbsp; & nbsp; V の = s □ × h △ 3 = 30 & amp; sup2; × 30 √ 2 △ 3cm & amp; sup3; = 9 √ 2DM & amp; sup3;

Each of the right eight faces is an equilateral triangle with four vertices a, B, C and D in the same plane. ABCD is a square with a side length of 30cm. What is the figure

A solid composed of two regular triangles

10. As shown in Figure 5, if the side length of square ABCD is 8, M is on DC, DM = 2, and N is a moving point on AC, then the minimum value of DN + Mn is ()
A．8 B．8 C．2 D．10
Sorry, I forgot

It is known that DN = BN
So DN + Mn = BN + Mn
Because the line between two points is the shortest
So when n is at the intersection of BM and AC, it satisfies the problem
So in RT triangle BMC
BM=10
The minimum value of DN + Mn is 10