2 cos (45 + x) cos (225 - x) 2 cos (45 + x) cos (270 - (45 + x) ) 2 cos (45 + x) (-sin (45 + x) ) - sin (45 + x + 45 + x) - sin (90 + 2x)
- cos (30 - x) sin (60 + x) - cos (30 - x) sin (90 - (30 - x) ) - cos (30 - x) cos (30 - x) - cos² (30 - x)
-12 sin (135 - x) sin (45 - x) - 12 sin (90 + (45 - x) ) sin (45 - x) - 12 (- cos (45 - x) ) sin (45 - x) 12 cos (45 - x) sin (45 - x) 6 sin (45 - x + 45 - x) 6 sin (90 - 2x) 6 cos 2x
Nomor dua
cos 20 cos 40 cos 80 = 1/8 sin 20 x (cos 20 cos 40 cos 80 ) = sin 20 x 1/8 1/2 sin 40 cos 40 cos 80 = 1/8 sin 20 1/4 sin 80 cos 80 = 1/8 sin 20 1/8 sin 160 = 1/8 sin 20 sin 160 = sin 20 sin (180 - 20) = sin 20 sin 20 = sin 20 ---------------------> sama nilainya ^_^
sin(20) sin(40) sin (60) sin (80) subsitusi kan nilai sin(60) = √3 /2 √3/2 [ sin(20) sin(40) sin(80) ] = (√3/2) sin(20) [ sin(40) sin(80) ] ingat rumus : sin A sin B = (1/2) [ cos(A - B) - cos(A + B) ] = √3/2 sin(20) (1/2)[ cos(40) - cos(120) ] = √3/4 sin(20) [ cos(40) + cos(60) ] = √3/4 sin(20) [ cos(40) + 1/2 ] = √3/4 sin(20)cos(40) + (√3/8) sin(20) = (√3/4)(1/2) [ sin(60) + sin(-20) ]+ (√3/8)sin(20) = (√3/8) [ (√3 / 2) - sin(20) ]+ (√3/8)sin(20) = 3/16 - (√3/8)sin(20) + (√3/8)sin(20) = 3/16
1 votes Thanks 4
clarala
terimakasih banyak....bagaimana dengan nmr yg lain?apa perlu saya upload ulang kak?
ImmanuelSinaga
Hehehe, maaf cuman segini :D
Lagian, saya harus pergi :D
Kapan dikumpulnya ?
---> ntar malam saya kerjain lagi, silakan di upload
2 cos (45 + x) cos (225 - x)
2 cos (45 + x) cos (270 - (45 + x) )
2 cos (45 + x) (-sin (45 + x) )
- sin (45 + x + 45 + x)
- sin (90 + 2x)
- cos (30 - x) sin (60 + x)
- cos (30 - x) sin (90 - (30 - x) )
- cos (30 - x) cos (30 - x)
- cos² (30 - x)
-12 sin (135 - x) sin (45 - x)
- 12 sin (90 + (45 - x) ) sin (45 - x)
- 12 (- cos (45 - x) ) sin (45 - x)
12 cos (45 - x) sin (45 - x)
6 sin (45 - x + 45 - x)
6 sin (90 - 2x)
6 cos 2x
Nomor dua
cos 20 cos 40 cos 80 = 1/8
sin 20 x (cos 20 cos 40 cos 80 ) = sin 20 x 1/8
1/2 sin 40 cos 40 cos 80 = 1/8 sin 20
1/4 sin 80 cos 80 = 1/8 sin 20
1/8 sin 160 = 1/8 sin 20
sin 160 = sin 20
sin (180 - 20) = sin 20
sin 20 = sin 20 ---------------------> sama nilainya ^_^
sin(20) sin(40) sin (60) sin (80)
subsitusi kan nilai sin(60) = √3 /2
√3/2 [ sin(20) sin(40) sin(80) ]
= (√3/2) sin(20) [ sin(40) sin(80) ]
ingat rumus : sin A sin B = (1/2) [ cos(A - B) - cos(A + B) ]
= √3/2 sin(20) (1/2)[ cos(40) - cos(120) ]
= √3/4 sin(20) [ cos(40) + cos(60) ]
= √3/4 sin(20) [ cos(40) + 1/2 ]
= √3/4 sin(20)cos(40) + (√3/8) sin(20)
= (√3/4)(1/2) [ sin(60) + sin(-20) ]+ (√3/8)sin(20)
= (√3/8) [ (√3 / 2) - sin(20) ]+ (√3/8)sin(20)
= 3/16 - (√3/8)sin(20) + (√3/8)sin(20)
= 3/16