Since AD 1 and BC 1 are parallel and equal, BC1m? (or the remaining angle) is the angle formed by non-planar straight line AD 1 and c1m.
△MBC 1，BC 1= 16+4=25，C 1M=22，BM=4+4+4=23，
According to the cosine theorem,12 = 20+8-815cos ∠ BC1m, ∴ cos ∠ BC1m = 215/kloc-0.
So ∠BC 1M=arccos2 has praise and tread. What's your comment on this answer? Put away comments//high quality or satisfaction or special types or recommended answers dottimewindow.iperformance & window.iperformance.mark ('c _ best',+newdate); Lawyer recommendation service: If your problem has not been solved, please describe your problem in detail and seek free professional advice through Baidu Law Professional Edition. Other similar questions 20 17-09-07(20 14? As shown in the figure, in the quadrangular cone P-ABCD, the plane PAD⊥ plane ABCD, ∠ ABC = ∠ BCD = 90, PA=PD=DC=CB= 12AB, E52016-1. Shanghai simulation) As shown in the figure, in the quadrangular cone P-ABCD, the bottom ABCD is rectangular, PA⊥ plane ABCD, PA=AD=2AB=2, and E is the midpoint of Pb .22016-12-01(20/kloc The second mode of Dongcheng District is shown in the figure. In the P-ABCD of the quadrangular pyramid, the PD⊥ plane ABCD, the bottom ABCD is rectangular, PD=DC=4, AD=2, and E is PC22016-10-31(2013 Nantong. ∠ PBC = 90, ∠PBA⊙ Verification: Plane ACE⊥ Single side B1BDD172016-03-15 (20/kloc-0 As shown in the figure, in a cube ABCD-A1B1C1D1with a side length of 2, e and f are the midpoint of B 1B and DC respectively. (1) Find the triangular pyramid E20 16-. The second model of Chongming County is shown in the figure. It is known that the bottom ABCD of the quadrangular cone P-ABCD is square, the plane ABCD of PA⊥, E and F is BC respectively, and the midpoint of PC is12016-08-09 (2013? The second model of Pudong New Area is shown in the figure. It is known that the side length of ABCD-a1b1d1bottom surface of a regular quadrangular prism is 2 and its volume is 16. M and n are edges BB 1, B 1C 1 1 respectively. & gt recommended for you: F.context('cmsRight', [{'URL':'/d01373f082025aaf511aa256e9edab64034f1a07? x-BCE-process = image % 2f resize % 2Cm _ lfit % 2Cw _ 450% 2Ch _ 600% 2c limit _ 1% 2f quality % 2Cq _ 85% 2f format % 2Cf _ auto '，' contractId':'A24KA00562 '，}，{ ' URL ':/s？ word = % E6 % AC % A7 % E6 % B4 % B2 % E6 % 9D % AF & sa = searchpromo _ ozb _ zhidao _ tuijian '，' src ':'/3 BF 33 a 87 e 950352 AAF 5 df 4954 143 fbf2b 2 1 18 b6b？ x-BCE-process = image % 2f resize % 2Cm _ lfit % 2Cw _ 450% 2Ch _ 600% 2c limit _ 1% 2f quality % 2Cq _ 85% 2f format % 2Cf _ auto '，' contractId ':' '，}])； Is Huaqiang North's second-hand mobile phone reliable? Why is the cost of cancer treatment getting higher and higher? What impact will the "network toilet" have? The price of electric cars has dropped many times. Is the quality guaranteed? I recommend f.context ('recbrand', [{"img": "\/86D6277F9E2F07083523F69DFB 24B 899A901F20d? x-BCE-process = image % 2f resize % 2Cm _ lfit % 2Cw _ 450% 2Ch _ 600% 2c limit _ 1% 2f quality % 2Cq _ 85% 2f format % 2Cf _ auto "，" url":"/hm.js？ 6859 ce 5a af 00 FB 00387 e 6434 E4 FCC 925 "； var s = document . getelementsbytagname(" script ")[0]； s.parentNode.insertBefore(hm，s)； })(); window . TT = 1720089437；