Current location - Training Enrollment Network - Mathematics courses - For example, on page 79, the answer to the first question in Group B is a compulsory test in senior one mathematics. In a square with a side length of 2
For example, on page 79, the answer to the first question in Group B is a compulsory test in senior one mathematics. In a square with a side length of 2
(1) thinks that ABCD is square, so a' is on BD after being folded in half, and BD ⊥ EF is A'D⊥EF because EF is parallel to AC and AC⊥BD.

(2) From the title, we can see that A'D⊥A'E, A'D⊥A'F, A'D⊥ plane A'EF, A'D⊥EF.

, A'D=2, A'E=A'F=3/2, be = BF = 1/4bc = 1/2, ef = 1/2 times the root number 2,

V triangular pyramid A'-EFD=SH/3=S triangle a' ef * a'd/3 =1/2nd radical 17 * 2/3 =1/3rd radical17.