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

The capulet and montague families love writing. last year, each capulet wrote 444 essays, each montague wrote 666 essays, and both families wrote 100100100 essays in total. this year, each capulet wrote 888 essays, each montague wrote 121212 essays, and both families wrote 200200200 essays in total. how many capulets and montagues are there? choose 1

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?