1) As can be seen from the figure, the triangle ABC is the Rt triangle.

So ABF angle +CBF angle +ACB angle =90 degrees.

Because arc BA= arc AF

Angle ACB= angle ABF

therefore

Angle ACB = (90 degrees) /2

(2) Arc BA= Arc AF

Angular ACB= angular ballistic missile

Another angle BAC= angle ADC=90 degrees

therefore

Similar to triangle ACB

Angle EMA= angle EAM

AEM is an isosceles triangle.

Have AE=EM

Easy to know: triangle and similar triangles cab

Angle EBA= angle EAB

Abe is an isosceles triangle.

There is EB = AE

So there is

BE=EM