How to find the values of sin150 and cos180 degrees?

Define your question better:

You mean now how to find or the answer?

Well if you ask how to find then you need to use the unit circle.

http://en.wikipedia.org/wiki/Unit_circle

Unit circle is a circle in the origin ( y = 0 x = 0 ) and the borders of the circle are always 1.

If you think that x and y is a triangle with 90 degrees angle and corners would be in the circle borders so they would be 1 and your angle is in the upper corner then cos would be the bar next to you divided with hypotenuse and sin would the bar against you divided with the hypotenuse right? So you can cut the hypotenuse out because it's the same in both of them.

So when people talk about cos x they talk about the desired value going up and down the y axle because it's the bar next to you, right? So cos 0 would be 1 because it starts from the top and cos 180 then it would be -1 ( the angle is in the origin x = 0 y = 0 ).

And when people talk about sin x then the desired value is in the x axle so when you need to think about the x axle ( note you want only the y value as the answer ). So when it's sin 90 it's always 1 because the angle from each side in the circle is 1 so sin 150 would be the same as sin 30 because it's the same y value, right? x value doesn't matter.

Plus when talking about values in the unit circle people like to give them as radian angles so 180 is always π and 360 is 2π so 150/180 would be 150/180π = 5/6π and sin 5/6π would be the same as sin1/6π. Got it? It's pretty simple.

Hello

See my answer to your other question

150 = 90 + 60 = π/2 + π/3

180 = 2π

Cos 2π = -1 you know that by the trigonometric circle

sin(π/2 + x) = cos(x) and you know that cos π/3 = √3/2

That value is in the basic table that you are supposed to know

Hope it helped

Bye !

sin 150 = sin (60 +90 )

sin 150 is in the 2nd quadrant has a negative sign so

- sin 60 will be the answer

- sqrt 3 /2

I consider so however only if you do it from a legit online institution ! Certainly it would be precious for you do pursue a measure on-line if you're into a full time job ( there will not be much options left i assume if you find yourself in a full time job). It's better to have education instead than now not having it in any respect. So i might say go for it.

i) sin(150°) = sin(180° - 30°) = sin(30°) = 1/2 [sin(180° - x°) = sin(x°)]

ii) cos(180°) = cos(180° - 0°) = -cos(0°) = -1 [cos(180° - x°) = -cos(x°)]

@ Good guy:

180° is not equal to 2π

It is equal to π only.

cos(π/3) is not equal to √3/2

It is equal to 1/2 only.