∠a and ∠b are complementary angles of right triangle abc, cos a = 0.83, and cos b = 0.55. what is sin a + sin b?

a) 0.28

b) 1

c) 0.38

d) 1.38

One cell phone plan charges $20 per month plus $0.15 per minute used. a second cell phone plan charges $35 per month plus $0.10 per minute used. write and solve an equation to find the number of minutes you must talk to have the same cost for both calling plans.