The cosine of 180 degrees is -1. This value represents the x-coordinate of the point on the unit circle at an angle of 180 degrees, which corresponds to the point (-1, 0). Therefore, (\cos(180^\circ) = -1).
cos 255 deg = - 0.2588 <-----[ Answer ]
To find the six trigonometric functions of 180 degrees, we can use the unit circle. At 180 degrees, the coordinates of the point on the unit circle are (-1, 0). Thus, the sine function (sin) is 0, the cosine function (cos) is -1, and the tangent function (tan) is 0. Consequently, the values for the six trig functions are: sin(180°) = 0, cos(180°) = -1, tan(180°) = 0, csc(180°) is undefined, sec(180°) = -1, and cot(180°) is undefined.
sin(0) = 0, sin(90) = 1, sin(180) = 0, sin (270) = -1 cos(0) = 1, cos(90) = 0, cos(180) = -1, cos (270) = 0 tan(0) = 0, tan (180) = 0. cosec(90) = 1, cosec(270) = -1 sec(0) = 1, sec(180) = -1 cot(90)= 0, cot(270) = 0 The rest of them: tan(90), tan (270) cosec(0), cosec(180) sec(90), sec(270) cot(0), cot(180) are not defined since they entail division by zero.
The cosine of 150 degrees is equivalent to the cosine of 180 degrees minus 30 degrees, which can be expressed as (-\cos(30^\circ)). Since (\cos(30^\circ) = \frac{\sqrt{3}}{2}), it follows that (\cos(150^\circ) = -\frac{\sqrt{3}}{2}). Therefore, (\cos 150^\circ = -\frac{\sqrt{3}}{2}).
A Quadrantal angle is an angle that is not in Quadrant I. Consider angle 120. You want to find cos(120) . 120 lies in quadrant II. Also, 120=180-60. So, it is enough to find cos(60) and put the proper sign. cos(60)=1/2. Cosine is negative in quadrant II, Therefore, cos(120) = -1/2.
cot x = (cos x) / (sin x) cos (x - 180) = cos x cos 180 + sin x sin 180 = - cos x sin (x - 180) = sin x cos 180 - cos x sin 180 = - sin x cot (x - 180) = (cos (x - 180)) / (sin (x - 180)) = (- cos x) / (- sin x) = (cos x) / (sin x) = cot x
cos(125) = cos(180 - 55) = cos(180)*cos(55) + sin(180)*sin(55) = -cos(55) since cos(180) = -1, and sin(180) = 0 So A = 55 degrees.
the answer is 180 degrees; since cos 180⁰ = -1, then cos-1 -1 = 180⁰ mathematically cos-1-1 here calculator is required and you'll get answer 180 degrees.....
Cos(-155) = cos(155) = 1 - cos(180-155) = 1-cos(25).
cos 255 deg = - 0.2588 <-----[ Answer ]
If ø is an obtuse angle then (180 - ø) is an acute angle and: sin ø = sin (180 - ø) cos ø = -cos (180 - ø) tan ø = -tan (180 - ø)
cos(195) = cos(180 + 15) = cos(180)*cos(15) - sin(180)*sin(15) = -1*cos(15) - 0*sim(15) = -cos(15) = -cos(60 - 45) = -[cos(60)*cos(45) + sin(60)*sin(45)] = -(1/2)*sqrt(2)/2 - sqrt(3)/2*sqrt(2)/2 = - 1/4*sqrt(2)*(1 + sqrt3) or -1/4*[sqrt(2) + sqrt(6)]
cos(180°) = -1, so it is not always positive.
sin(180) = 0 cos(180) = -1 tan(180) = 0 cosec(180) is not defined sec(180) = -1 cot(180) is not defined.
Cosine(90) = 0 NB Cosine(0) = 1 Cos(30) = 0.8669... Cos(45) = 0.7071... Cos(60) = 0.5 Cos(90) = 0 Cos(120) = -0.5 Cos(0135) = -0.7071... Cos(150) = -0.8660... Cos(180) = -1 NB #1 ; refer to your (scientific) calculator or #2 ; refer to Castles Four Figures Tables. NNB Note the negatives (-) between 90 & 180.
It's not. The tangent of 180 degrees is zero. Consider tan(x) = sin(x)/cos(x). When x = 180 degrees, sin(x) = 0 and cos(x) = -1 and so tan(x) = 0
y = cos ( x ). z = cos ( x + 180 degrees ).