I need help with this i can’t graph

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

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8

How do you write something in scientific notation?