Sum Difference Trig

Given sin α = -3/5, cos α = -4/5 and cos β = (2√5)/5, sin β = (-√5)/5
Please find the sum or difference:
sin (α-β)=

• 0

• (-10√5)/25

• (√2-√6)/4

• (√8)/4

If A and B are first quadrant angles with sinA=15/17 and cosB=4/5, find cos(A - B).

• 3/8

• 8/17

• -13/85

• 77/85

(sinu)(cosv) + (cosu)(sinv) =

• cos(u - v)

• cos(u + v)

• sin(u - v)

• sin(u + v)

(sinu)(cosv) - (cosu)(sinv) =

• cos(u - v)

• cos(u + v)

• sin(u - v)

• sin(u + v)

(cosu)(cosv) - (sinu)(sinv) =

• cos(u - v)

• cos(u + v)

• sin(u - v)

• sin(u + v)

(cosu)(cosv) + (sinu)(sinv) =

• cos(u - v)

• cos(u + v)

• sin(u - v)

• sin(u + v)

(tanu + tanv)/(1-(tanu)(tanv))

• tan(u - v)

• (tanu)(tanv)

• tan(u + v)

• tanu - tanv

Write the expression as the sine or cosine of a single angle:

$\cos\left(7y\right)\cos\left(3y\right)-\sin\left(7y\right)\sin\left(3y\right)$

(tanu - tanv)/(1+(tanu)(tanv))

• tan(u - v)

• tanu - tanv

• tan(u + v)

• None of the above