SIN function

I have a formula that goes like this;

Fhk = Fh0k / K90 * sin^2 alpha + cos^2 alpha

At this point in time alpha is 90 degrees.

Using my calculator (with degrees setting) i get sin 90 = 1

However in excel even typing into a separate cell =sin(90) i get 0.8939

This result is in radians, but i dont want it in radians, i only want it in degrees.

Is this an excel setting or do i need to specify in the formula that i want a result in degrees??

Thanks

Tom