Respuesta :

This is an isosceles triangle because the picture shows it has two equal sides. Isosceles triangles have two equal angles.

The sum of all the angles of a triangle = 180º.

We can use this equation to solve for x:

2x + 54 = 180.

     - 54    -54     Subtract 54 from both sides.

2x = 126

/ 2     /2  Divide 2 from both sides to isolate x.

x = 63º

Let's check! 63 + 63 + 54 = 180? YUP!