What property is 1 • 4 = 4? ¿? i forgot lol

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

What is the solution to the system of equation graphed belowa.(0,-4)b.(2,5),1),-3)

Convert 3,200,000 to a scientific notation.