How do we call a function whose graph is a straight line

(98 points) i need with 5 questions. answer definitions are welcomed, but not necessary.

16. you're planning to buy a boat, a motor, and some miscellaneous boating equipment. the boat costs $325, the motor costs $225, and the equipment costs $79. if you've saved $438 toward these purchases, how much more do you need to save? a. $181 b. $281 c. $291 d. $191

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.