Question

Fie ABCD un patrulater convex cu m(∡A) =100° , (∡B ) =80° si m(∡C) =120°.Determinati masura ∡D.

Answer 1

m(A) +m(B) +m(C) +m(D) =360°
m(D) =360°- m(A) - m(B) - m(C)
m(D) =360°-100°-80°-120°
m(D)=60°