Question

Patrulaterul convex ABCD are m ( <A)=60 grade , m(<B)=90 grade , m(<D)=120 grade .Aratati ca patrulaterul ABCD este trapez dreptunghic.

Answer 1

A, B, C, D - unghiuri
A+B+C+D=360 grade

60+90+120+C=360
270+C=360
C=90 Grade

Si avem, C=90 Grade, B = 90 Grade=> ABCD trapez dreptunghic