How do I solve this: 180° − (45° + 90°)?

What basic trigonometric identity would you use to verify that sin x cos x tan x =1-cos^(2)x?

5500 dollars is placed in an account with an annual interest rate of 6.5%. to the nearest tenth of a year, how long will it take for the account value to reach 19700 dollars?

Which system of linear inequalities is represented by the graph?