The equation y = 20sin(0.5θ - 2) + 40 models the monthly temp for a certain city.

Use the equation to predict the temperature in the city during December. Thanks

3 answers

assuming θ is the month, just plug in θ=12.

Come on back if you don't like the answer.
Still don't get it, so yes need more help.
Did you make sure your calculator was set to Radians ?
(press DRG until you see RAD displayed)

Here are my keystrokes

.5
x
12
-
2
=
sin
=
x
20
+
40
=

and you should get 24.86°

(Of course you can see that since sin(????) ranges from -1 to +1, the temperature must range from a minimum of 20 to a maximum of 60, so hoping the units are Fahrenheit and not Celsius
Sounds like rather dismal place to be )