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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 variable in a relation who’s value depends on the value of the independent variable is called what?

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?