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which sum or difference identity would you use to verify that cos (180° - q) = -cos q?

a.

sin (a -b) = sin a cos b – cos a sin b

b.

cos (a -b) = cos a cos b – sin a sin b

c.

cos (a -b) = cos a cosb + sin a sin b

d.

sin (a + b) = sin a cos b + cos a sin b

2.find all solutions for a triangle with a=140,b=10 and a=3. round to the nearest tenth.

a.

b = 15.4°; c = 147.6°; c = 20.2

c.

b = 15.4°; c = 134.5°; c = 20.2

b.

b = 16.2°; c = 147.6°; c =20.2

d.

no solutions