. дьа дьалмдчдмадььд box. KS. Ken dkncdk. my x king DJ NBC kn kx just / just. know. my class. KS. can. Jan kx. kx just ND knocks nkdn DJ. Jan dk djn DJ. kid. Jan kdn kdn kid. jdnicnd k x ft jndkcdndj. dkcndkcnkd kdnckdcjd ckdc not. don't know dank. can. kx NC kdnckdnckdnckdn MD. no XML ndkncdkncksbcdj CDMA. kdnckdnckdnckdn Cmdr cjdjckd cmd. kdnckdnckdnckdn de ND. ND cm decks cmd club cmd know damn my Xmas. do. ND. Xmas. dknckdncdknckdisckd kx. Xmas. kx. MD. kx. kdn kdn dknckdncdknckdisckd DNA doesn't need done. my DJ. kid ndjnckd. MD. MD. MD me. keep doing k ndkcndmc dknckdncdknckdisckd cmd cmd. kx. kx ckdncdkncdkcndknckdncmx. MD. MD. ; do MD. MD. know wdk. FM. FM for kids just. Xmas. clothes. DJ. kx. Xmas. kx not x my. don't kx. DJ. just. kx а б. да. бч бс б. б. ба MD да. ба. да. адм да. да. ад. ба. б а б да. да. ба. бс. бс. бс. а б сб. бс. бс. с днем рождения
Вычислите:
1) sin 105° * sin 75°; 2) 4sin 37,5° * sin 7,5°; 3) 8sin 22,5° * cos 7,5°
1 ) sin 105° * sin 75° = (1/2)* (cos(105° -75°) - cos(105°+75°) )=
(1/2)* (cos30°-cos180°) =(1/2)* ( (√3)/ 2 - (-1) ) = (1/2)*((√3) / 2+ 1 ) = (√3+2)/4
- - - - - - -
2 ) 4sin 37,5° * sin 7,5° =2*(cos(37,5° - 7,5°) - cos(37,5° +7,5°) ) =
2*(cos30° - cos45°) =2*( (√3)/2 -(√2) /2) = √3 - √2 .
- - - - - - -
3 ) 8sin 22,5° * cos 7,5° = 4*( sin(22,5°+7,5°) +sin(22,5°-7,5°) ) =
4*( sin30° + sin15° ) = 4*( 1/2 + sin(60 - 45°) ) =
4*( 1/2 + sin60°*cos45°- cos60°*sin45° ) = || cos45°=sin45 =√2 / 2 ||
= 4*( 1/2 + √2 (√3 - 1) / 4 ) = 2 + √6 - √2 .
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
P.S. sin15° =sin(45° -30°) = sin45°*cos30° - cos45°* sin30° =
(√2 / 2)*(√3 / 2 -1 / 2) = (√6 - √2) / 4 .
sin15° =√( (1 -cos30°) / 2 ) =√( (1 -√3 /2) / 2 ) =√( (2-√3 ) / 4 ) =
√( (4-2√3 ) / 8 ) =√( (3-2√3+1) / 8 ) =√( (√3 - 1 )² / 8 ) = (√3 - 1) /2√2 =
√2(√3 - 1) /4 = (√6 - √2) / 4 .
Пошаговое объяснение: