Question

Patrulaterul convex ABCD are m(A)=m(C)=m(B)+m(D).
Aflati m(unghiului C)

Answer 1

m(A)+m(B)+m(D)+m(C)=360
m(A)+m(A)+m(A)=360
3m(A)=360
m(A)=360:3=120=m(C)