Guys help me please ,how to solve it? i need a solution

On new year's day, the average temperature of a city is 5.7 degrees celsius. but for new year's day 2012, the temperature was 9.8 degrees below the average. i) if a represents the average temperature on new year's day and 7 represents the temperature on new year's day 2012, what formula accurately relates the two values together? ii) what was the temperature on new year's day 2012? dt a 0.8 ii) - 4 1 degrees celsius da-t-98 ii) 59 degrees celsius 1) 7 = -9,8 11) 59 degrees celsius ii) l degrees celsius

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?