Question

Cos 155 degrees equals

Answer 1

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

Answer 2

type cos(155) into a calculator

cos(155)= -0.906307787...