Respuesta :

Rule of trigonometric functions:-

sin a = cos(90 - a)

Here a = 90°.

sin 90 = cos (90 - 90)

1 = cos 0.

cos 0 = 1.


So the cos 0 = 1.

Answer:

Step-by-step explanation:

If sin 90 = 1

then cos 0 will be

as we know that

cosx = sin(90-x)

If we plug x = 0 ,

cos0  = sin 90 = 1