Given:
cos 120°
To find:
The exact value of cos 120° in simplest form with a rational denominator.
Solution:
We have,
It can be written as
![[\because \cos (90^\circ-\theta)=-\sin \theta]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Ccos%20%2890%5E%5Ccirc-%5Ctheta%29%3D-%5Csin%20%5Ctheta%5D)
![[\because \sin 30^\circ=\dfrac{1}{2}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Csin%2030%5E%5Ccirc%3D%5Cdfrac%7B1%7D%7B2%7D%5D)
Therefore, the exact value of cos 120° is 
.
It would be -1.2
hope i helped follow me
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8 * 2/3
16/3
Hope this helps!
For #2 an easier way to solve problems like this is to move the decimal point to the left twice in this case it’ll be 0.15 instead of 15% now you multiply 35 by 0.15 which is 5.25 now you add the total price and the tip 35+5.25=40.25 and there’s your answer
