If a and b are integers and b cannot equal 0, which of the following must be true about a over b?

What is the base of 1/9 to the power of 2

What is the value of x in the this question ?

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b