What variable(s) are classified as nominal variable(s)?

Which of the following is correct interpretation of the expression -4+13

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

Complete the equation of the live through (-1,6) (7,-2)