P-20 =30 as a additon equation

Which expression is equivalent to? assume x > 0 and y > 0.

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

Choose the correct slope of the line that passes through the points (1, -3) and (3, -5)