May 25, 2018 · -1 Within the unit circle, cosine provides the x coordinate of a point on the surface of the circle. Sine provides the y coordinate of a point on the surface of the circle. At 180^o, the point on the unit circle surface is (-1,0). So this means: x=cos(180^o) = -1 y=sin(180^o) = 0 To find the exact value of cos(180^o) -sin(180^o) -1 - 0 = -1

May 23, 2016 · Please see below. One of the easiest ways could be to use the formula cos(A-B)=cosAcosB+sinAsinB Hence, cos(180^o-theta)=cos180^ocostheta+sin180^osintheta = (-1)xxcostheta+0xxsintheta = -costheta

Jul 14, 2016 · Apply the trig identity: cos (a - b) = cos a.cos b + sin a.sin b cos (180 - a) = cos 180.cos a - sin 180.sin a ...

Mar 7, 2018 · Use the sum in cosine identity, cos(A+ B) = cosAcosB - sinAsinB. Thus we have: cos(180˚)cos(x) - sin(180˚)sinx = -cosx -1(cosx) - 0(sinx)= -cosx -cosx= -cosx LHS ...

Jun 27, 2016 · Use the trig identity: cos (a + b) = cos a.cos b - sin a.sin b cos (180 + a) = cos 180.cos a - sin 180.sin a Trig table -->

Oct 30, 2015 · cos-120^@=-1/2=-0,5 cos(-120^@)=cos120^@ =cos(180^@-60^@) =-cos60^@ =-1/2. Note: Above I have used the 180^@ rule. Alternatively I could also have used the 90^@ rule, or the compound angle formulae for either sin or cos, or a number of other possible methods as well, and each would result in exactly the same final answer. Since the question did not …

Oct 1, 2015 · At #270^@# for a unit radius circle #color(white)("XXX")sin(270^@) = ("opposite")/("hypotenuse")# #color(white)("XXXXXXXXX")=y/sqrt(x^2+y^2)#

Sep 18, 2015 · Plug in the following values. tan 180 =0 cos 180= -1 csc 270= csc (360-90)= csc -90 =-csc 90 =-1. sin 90= 1. This would make 0-2-3+1= -4

Jan 4, 2017 · How do you find the exact value of #cos 180#? Trigonometry Right Triangles Trigonometric Functions of Any Angle. 1 Answer

May 10, 2015 · Cos 135° is an angle in the second quadrant. In the second quadrant, cos is negative. #Cos theta = x/r# #Cos 135 = cos(180-45) = -cos 45°#