Triangle ABC is similar to triangle CEF.
Explanation:
Diagram is inserted for the reference.
ABCD is a rectangle.
ABC is a right angled triangle because all the angles of the rectangle are 90◦ - (a)
CEF is a right angled triangle because FE is perpendicular to DC – (b)
In triangles ABC and CEF,
1. Angle ABC = Angle CEF = 90◦ (Both are right angles from a and b)
2. Angle BCA = Angle EFC (Alternate angles on parallel lines are equal on intersection)
Hence using Similarity property of AA (Angle, Angle), Triangle ABC and CEF are similar.
