The length of D'N must be required, and the side length must be known first.
Then connect your D'B so that D'B'N is a right triangle.
Assuming the side length is 1, it is easy to conclude that B'D' is the "root number 2" in the bottom surface A'B'C'D'. Then n is the midpoint. B'N is "half"
Then there is Pythagorean theorem. D'N equals NB' plus B'D'.
2. 1. As we all know, the volume of a ball is equal to the volume of a cube. Compare the surface areas of spheres and cubes.
4/3*πr^3 = a^3->； A = (4/3 * π) (1/3) * r, s sphere = 4 * π r 2, s square = 6 * A 2,
3. It is known that the points P, PA⊥ plane ABCD, E and F outside the rectangular ABCD plane are the midpoint of AB and PC respectively. Verification: EF⊥CD.
Connect AC, where the point is G, the projection of F on ABCD is G, EG is the projection of EF on ABCD, and EG is perpendicular to DC, so EF is perpendicular to DC.
The length of each side of a parallelepiped is 4. On the three sides starting from the vertex P, take PA= 1, PB=2 and PC=3 respectively, and the volume of the pyramid P-ABC is several times that of the original parallelepiped.
If the triangle PAB is the base, S is the parallelepiped 1/2*`4* 1/2.
When the height is 3/4 times of the original height, the volume is multiplied by 1/3 and 1/64.
5. Let the vertices A and B of △ABC be out of plane α, and the vertex C be in plane α. The projection of AB on α is A 1, B 1, AA 1 < BB 1, and the height of △ABC on the BC side is AD, forming an AD‖ plane α, BC, α.
AD is perpendicular to BC, and AD || A A, B, C and D are coplanar. The answer is the angle formed by BC and a.
6. It is known that straight lines A and B are non-planar straight lines, and straight line C is parallel to A and C and B do not intersect. Prove that b and c are non-planar straight lines.
Reduction to absurdity. If b and c are not straight lines on different planes, and because b and c do not intersect, b and c are parallel.
And because A and C are parallel, A and B are also parallel.
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Four schools in the second semester (13 middle school, 17 middle school, 4 1 middle school and overseas Chinese)
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Review of Unit 5, Volume 4 of Chinese in Senior High School
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Binomial theorem of permutation and combination in synchronous test of senior three.
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Comprehensive Teaching Quality of Science in Senior Three in Shaoxing City, Zhejiang Province in 2007
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In 2007, Zigong City, Sichuan Province ∴ ordinary high school, comprehensive physical fitness of liberal arts.
Liuzhou No.1 Middle School 07 Senior Three Comprehensive Ability Test (9)
∴ Tianfu famous school 479 simulated strengthening the comprehensive ability of liberal arts examination paper
Guangdong Nanhai District ∴ Guicheng Middle School 2007 Senior Three Comprehensive Arts
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∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (
∴ 2007 National Unified Entrance Examination for Colleges and Universities (