It is known that, as shown in the figure, a is a point on EF, and the quadrilateral ABCD is a parallelogram with ∠ ead = ∠ BAF. (1) prove that △ CEF is an isosceles triangle. (2) which two sides of △ CEF are equal to the perimeter of the parallelogram ABCD? Prove your conclusion

It is known that, as shown in the figure, a is a point on EF, and the quadrilateral ABCD is a parallelogram with ∠ ead = ∠ BAF. (1) prove that △ CEF is an isosceles triangle. (2) which two sides of △ CEF are equal to the perimeter of the parallelogram ABCD? Prove your conclusion

(1) It is proved that: ∵ quadrilateral ABCD is a parallelogram, ∵ ad ∥ FC, ab ∥ EC, ∵ Fab = ∵ e, ∵ ead = ∵ F. and ∵ ead = ∵ BAF, ∵ e = ∵ f. ∵ CEF is an isosceles triangle. (2) conclusion: CE + CF = perimeter of parallelogram ABCD Length = AB + BC + CD + ad = BF + BC + CD + de = CE + CF