Then a (1, 0,0), b (0 0,0 1, 0), a 1 (1, 0,3). Let d (0, 0, a).
M = (1, 1, 0) is the normal vector of plane A 1AB, and let n=(x, y, z) be the normal vector of plane A 1BD.
DA 1=( 1，0，3-a)，DB=(0， 1，-a)，
By DA 1？ n=0，DB？ N=0，x+(3-a)z=0，y-az=0，x=3-a，y=-a，z=- 1，n=(3-a，-a，- 1)。 (4 points
Question, | cos < m, n > | = | m? n||m||n|=|3？ 2a|2×(3？ A)2+a2+ 1=|-36|= I have praised it and stepped on it. 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 provide free professional consultation through Baidu Law Professional Edition. Other similar problems are shown in figure 2011-0/-04. In the straight triangular prism ABC-a1b1,AB=AC. O are aa 1.a 1c 1, and b1-in ABC-a 1b 1c65438. Verification: MN⊥ plane A1B132020-03-26 in triangular prism ABC-A1B1,D is the midpoint of AC. Verification: B 1C parallel plane A65448. It is proved that ABC-A1B112012-1AB1/Plane DBC1/Kloc-0. Verification: Ab = AC = 1+0+0, AA, in AB1DC 32013-01straight triangular prism ABC-a1b/kloc-0. Verification: the AD⊥ plane A1DC1.2201KLOC-0/2-19 is in the triangular prism AC=BC-A1B1C/. It is proved that point D is the midpoint of AB: the plane CA 1D is perpendicular to the plane aa 1bb 16200 triangular prism ABC-A1B1C1,and D is the midpoint of AC. Prove: & 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 ':' '，}])； The price of electric cars has dropped many times. Is the quality guaranteed? What impact will the "network toilet" have? Is Huaqiang North's second-hand mobile phone reliable? Why is the cost of cancer treatment getting higher and higher? 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 = 1720054367；