Question

find the value of cos390° ​

Answer 1

To obtain 390 degrees in radian multiply 390° by / 180° = 13/6 .

Answer 2

Answer:

cos 390° = ½

Step-by-step explanation:

cos390° = cos(90°+90°+90°+90°+30°)

cos390° = 4cos90° + cos30° = 4(0) + ½

cos 390° = 0+½ = ½

• cos 390° = ½