How many solutions d+6+2d=4d+9

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

Planning for the possibility that your home might get struck by lighting and catch on fire is part of a plan

Which expression is equivalent to sq-80