Answer:
-0.9063077
Step-by-step explanation:
The cos of 155 degrees is equals to -0.9063077
To obtain cos 155 degrees in radian multiply 155 by π/180
cos 155 degrees = (155 /180) π radian
Dividing 155 and 180 by its common factor 5 we will get (31/36)π
so cos 155 in terms of radian is equals (31/36)π
Since our angle is greater than 90 degrees and less than or equals to 180 degrees, it is located in quadrant II . In second quadrant the value of sin are positive only that is why cos 155 is -0.9063077
It can also be solved by using identities of cosine
cos (∅) = sin(∅-90)
putting ∅ = 155, we get
= sin(155-90)
= sin(-65)
= -0.9063077
