Write the product of 7×2×7×2×7 in exponential form

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

Ineed with number 6 , explain how to get 1978

Can somebody 1. what is the formula for finding the vertical distance between two points on a coordinate plane?