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

Option C is correct

Step-by-step explanation:

We know tha tCos(A-B) = cosA cosB + sinAsinB

Plugging A = 180 and B = Ф

cos(180-Ф)= cos180cosФ+sin180sinФ

                  = (-1) cosФ+ (0) sinФ   [ since cos180=-1 and sin180 =0]

                 = -cosФ + 0

                 = -cosФ

Therefore option C is the correct answer.        

guess at question:

a vertical line intersects the graph of g(x,y) = 0 at two points. what conclusion follows about the function f(x) implicitly defined by g(x,f(x)) = 0?

the domain of f(x) cannot include the x coordinate of any such vertical line.

informally, f(x) is not a function, and

g(x,y)=0 cannot be solved for y uniquely.

the relation r = {(x,y) such that g(x,y) = 0} is a function if

for all (a,b) ∊ r and (c,d) ∊ r, a=c implies b=d.

step-by-step explanation: