Hey.

1- Express 12cosx+ 9sinx in the form Rcos(x-A) where R is greater than 0 and A is between 0 and 90.

I did this one and got 15cos(x-0,644) (in radians)

I cant do the second part.

b) Use the method of part a to find the smallest positve root of A of the equation 12cosx+9sinx = 14

Thanks.