Notice that based on the diagram, all of the sides of the triangle are the same length. (The dashes on the sides of the triangle show that the sides are of congruence.) This means that the triangle is an equilateral triangle. An important thing to note about equilateral triangles is that they all have angles of 60°. All angles in equivalent triangles are 60°.
This means that we can set equal to 60 to solve for
:
- Set up
- Add 3 to both sides
- Divide both sides by 7
Our answer is x = 9.