Cos 155 degrees equals

type cos (155) into a calculator

cos (155) = - 0.906307787 ...

-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