2007-12-30 14:10:47 · 9 answers · asked by Kelly S 1 in Science & Mathematics ➔ Mathematics
cos(345) --> cos(a+b)=cosacosb-sinasinb
= cos(300+45)
= cos(300)cos(45) + sin(300)sin(45)
= (1/2)(1/√2) - (-√3/2)(1/√2)
= (1/2√2) + (√3/2√2)
= (√6+√2)/4
2007-12-30 14:16:58 · answer #1 · answered by ¿ /\/ 馬 ? 7 · 0⤊ 1⤋
cos(345°)
= cos(360°-15°)
= cos(15°)
= cos(45°-30°)
= cos(45°)cos(30°) + sin(45°)sin(30°)
= (1/â2)(â3/2) + (1/â2)(1/2)
= â3/2â2 + 1/2â2
= â3â2/4 + â2/4
= (â6+â2)/4
2007-12-30 14:20:04 · answer #2 · answered by gudspeling 7 · 1⤊ 1⤋
cos(345)
= cos(15)
= cos(45-30)
= cos(45)cos(30)+sin(45)sin(30)
= ( â3 + 1)/(2â2)
= (â6+â2)/4
= 0.96592582628907
cos(345)
= cos(15)
= â[(1+cos(30))/2]
= â(2+â3)/2
= 0.96592582628907
2007-12-30 14:20:40 · answer #3 · answered by sahsjing 7 · 0⤊ 1⤋
The same as the exact value of cos(15)
2007-12-30 14:53:57 · answer #4 · answered by michael_p87 2 · 0⤊ 1⤋
cos 345° = cos 15°
cos 15° = cos (60 - 45)°
cos 60° cos 45° + sin 60° sin 45°
(1 / 2) (1 / â2) + (â3 / 2) (1 / â2)
(â3 + 1) / (2â2)
2007-12-31 06:40:16 · answer #5 · answered by Como 7 · 0⤊ 0⤋
(1 + â3)/(2 â2)
2007-12-30 14:14:46 · answer #6 · answered by David G 6 · 0⤊ 1⤋
.96592582628907
or
(sq root (3) + 1) X (sq root 2)/4
2007-12-30 14:21:39 · answer #7 · answered by Deuce 1 · 1⤊ 1⤋
square root of 6 + square root of 2
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4
2007-12-30 14:17:20 · answer #8 · answered by Anonymous · 1⤊ 1⤋
0.9659
2007-12-30 14:17:12 · answer #9 · answered by sharday b 1 · 0⤊ 3⤋