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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

The jewelry store is having a sale. necklaces that were regularly priced at $23.50 are on sale for $18.80. what is the percentage of decrease in the price of necklaces?

If the discriminant if a quadratic equation is 4 which statement describes the roots?