HELP! First to actually give the correct answer gets the brainliest

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

Which graph corresponds to the function f(x) = x2 + 4x – 1?

What does the sign of the slope tell you about a line?