I need the answers quickly. It’s 12x+6 21x-1 and 11x+1

34

Step-by-step explanation:

Sum of interior angles in a triangle is 180,

26x + 6 + 11x + 1 + 21x - 1 = 180

26x + 11x + 21x + 6 + 1 - 1 = 180

58x + 6 + 0 = 180

58x = 180 - 6

58x = 174

x = 174 / 58

x = 3

m∠C = 11x + 1

        = 11 ( 3 ) + 1

        = 33 + 1

m∠C = 34

true? is that what you're asking or do you mean something else?

no not all of them.

step-by-step explanation:

some of them have a square base.