Answer:
x° = 61°
Step-by-step explanation:
Both of the "unknown" angles in the triangle are equal, since their opposite sides have equal lengths. (The triangle is isosceles.) The sum of angles in a triangle is 180°, so we have ...
58° + x° + x° = 180°
2x° = 122° . . . . subtract 58°, collect terms
x° = 61° . . . . . . . divide by 2
