Answer:
D. 60°
Explanation:
The interior angles of all triangles add up to 180 degrees.
There are two y's on the triangle
And one of the degree lengths is 60°, so we do:
2y + 60 = 180
Subtract 60 from both sides
2y + 60 - 60 = 180 - 60
2y = 120
Divide 2 from both sides
2y/2 = 120/2
y = 60°
Also, In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each other and are each 60°.
All three sides are equal
All the three interior angles are equal to 60 degrees
The interior angles of all triangles add up to 180 degrees.
Heres a picture of an equilateral triangle