2006-07-19 19:51:26 · 8 answers · asked by ND 2 in Science & Mathematics ➔ Mathematics
Method 1:
Given cos(x) = 0.8
we can deduce,
adj = 0.8
hyp = 1
opp = sqr(1^2 - 0.8^2) = sqr(.36) = 0.6
Therefore sin(x) = 0.6
Method 2:
Use the identity,
(sin(x))^2 + (cos(x))^2 = 1
(sin(x))^2 = 1 - (cos(x))^2
(sin(x))^2 = 1 - (0.8)^2
sin(x) = sqr(1 - 0.64)
sin(x) = sqr(0.36)
sin(x) = 0.6
2006-07-19 20:33:01 · answer #1 · answered by ideaquest 7 · 0⤊ 0⤋
Use the pythagorean identity (sinx^2 + cosx^2 = 1):
sin(x)^2 + cos(x)^2 = 1
sin(x)^2 = 1 - cos(x)^2 = 1-(.8)^2 = .36
Thus sin(x) = plus or minus sqrt[.36] = plus or minus 3/5.
There are two possible values of sine because cos[x]=.8 for two different values of x on the interval [0,2pi] (on that same interval cosx > 0 for x < pi/2 U 3pi/2 < x, while sinx > 0 for x < pi).
2006-07-20 03:14:12 · answer #2 · answered by David M 1 · 0⤊ 0⤋
(sinx)^2 + (cosx)^2 = 1
sinx = +sqrt(1 - (cosx)^2) = +sqrt(1 - 0.8^2) = +sqrt(1 - 0.64) = +sqrt(0.36) = +0.6
or
sinx = -sqrt(1 - (cosx)^2) = -sqrt(1 - 0.8^2) = -sqrt(1 - 0.64) = -sqrt(0.36) = -0.6
where sqrt means square root
2006-07-20 04:02:42 · answer #3 · answered by Dimos F 4 · 0⤊ 0⤋
cosθ = 0.8
so if we draw a right triangle we'll get a 6.8.10 triangle
and by using pythagorean theory
Sinθ = 0.6
tanθ = 0.75
2006-07-20 03:04:05 · answer #4 · answered by M. Abuhelwa 5 · 0⤊ 0⤋
Sine of the angle will be +/- (0.6)
2006-07-20 03:11:55 · answer #5 · answered by raj shekhar 2 · 0⤊ 0⤋
cosA = .8
A = cos^-1(.8)
sin(cos^-1(.8)) = .6
2006-07-20 11:15:53 · answer #6 · answered by Sherman81 6 · 0⤊ 0⤋
0.6 (by pythagorean theorem)
2006-07-20 03:01:00 · answer #7 · answered by emee_rocks 2 · 0⤊ 0⤋
0.6
2006-07-20 03:18:18 · answer #8 · answered by Maninder 2 · 0⤊ 0⤋