Fermi
·
Concept Library
·
Courses
·
Books
·
Problems
·
Simulations
·
Math Wiki
·
High School
Fermi
›
Problems
Mathematics
Mathematics
Problem
Let
U
U
U
be the set of all triangles in a plane. If
A
A
A
is the set of all triangles with at least one angle different from
60
∘
60^\circ
6
0
∘
, what is
A
′
A'
A
′
?
Browse the problem library