10 times posting the same thread and giving so little information...
I just see a screenshot with definitions of a serie of angles. Indeed of you define something as a = 2 or alfa = 30° it will appear as a slider. Nothing in the screenshot of your question (in none of the 10 ones as you repeatedly posted the same one) refers to a triangle nor to the three points shown above. You define a triangle with the triangle command or tool and then you can measure the angles. Or you can start with two points and using defined angles create a triangle in constructions I presume you know. But please send us one file that clearly shows what and how you defined to make question and eventual answer obvious.
But seeing the table icon, I presume you were working with the graphing calculator. In this app graphical features are removed, as indicates the pop up screen. So just read the message and use the Geometry app instead.
The same problem 
10 times posting the same thread and giving so little information...
I just see a screenshot with definitions of a serie of angles. Indeed of you define something as a = 2 or alfa = 30° it will appear as a slider. Nothing in the screenshot of your question (in none of the 10 ones as you repeatedly posted the same one) refers to a triangle nor to the three points shown above. You define a triangle with the triangle command or tool and then you can measure the angles. Or you can start with two points and using defined angles create a triangle in constructions I presume you know. But please send us one file that clearly shows what and how you defined to make question and eventual answer obvious.
But seeing the table icon, I presume you were working with the graphing calculator. In this app graphical features are removed, as indicates the pop up screen. So just read the message and use the Geometry app instead.
chris
Please post the .ggb file and we'll take a look!
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