2006-11-05 11:17:28 · 6 answers · asked by william r 1 in Science & Mathematics ➔ Mathematics
cos 75° = cos (45° + 30°)
= cos45°cos 30° - sin45°sin30°
=1/√2 * √3/2 - 1/√2 * 1/2
= (√3 - 1)/(2√2)
= (√6 - √2)/4
2006-11-05 11:25:13 · answer #1 · answered by Wal C 6 · 1⤊ 0⤋
Cos 75 Cos 15
2016-12-10 14:51:27 · answer #2 · answered by ? 4 · 0⤊ 0⤋
75 deg = 5/6 pi
so, cos 75 deg = cos 5/6 pi
This function does not have an "exact" value ... it works out to 0.259 (rounded), or (-√3)/2 per my trig cheat sheet in my math book
2006-11-05 11:22:36 · answer #3 · answered by dualspace 3 · 0⤊ 0⤋
The exact value of cos is 0.2588190451....numbers for on forever.
2006-11-05 11:22:03 · answer #4 · answered by Ero T 1 · 0⤊ 0⤋
cos(75) = cos(30 + 45)
cos(30 + 45) = cos(30)cos(45) - sin(30)sin(45)
cos(30 + 45) = (sqrt(3)/2)(sqrt(2)/2)) - ((1/2)(sqrt(2)/2))
cos(30 + 45) = (sqrt(6)/4) - (sqrt(2)/4)
cos(30 + 45) = (sqrt(6) - sqrt(2))/4
so
cos(75) = (sqrt(6) - sqrt(2))/4 or about .2558
2006-11-05 12:09:08 · answer #5 · answered by Sherman81 6 · 1⤊ 0⤋
0.2588'
2006-11-05 11:36:46 · answer #6 · answered by jamatri 2 · 0⤊ 0⤋