Question

Enter the number that belongs in the green box

Answer 1

Answer: 60°

The reason for this is because the image shows that ALL the sides are EQUAL. Therefore, all the angles must be equal.
So, we know that a triangle equals a total of 180°. If we simply divide that total by 3 we get 60°.

Answer 2

Equilateral triangles are triangles whose all sides and angles are equal.

Since the above given triangle has 3 equal sides it is an equilateral triangle.

So, the three angles of this triangle can be 3x.

Which means :

$=\tt 3x = 180$

$=\tt x = \frac{180}{3}$

$\hookrightarrow \tt \color{plum}x = 60°$

▪︎Therefore, x = 60°