Δ ABC ECHILATERAL
m (∡ABD)=10° si m (∡ACD) =20°
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ΔBDC DREPTUNGHIC?
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Δ ABC ECHILATERAL⇒m (∡ABC)=m (∡BCA)=m (∡BAC)=60°
m (∡ABD)=10° si m (∡ACD) =20°
m (∡DBA)=m (∡ABC)-m (∡ABD)=60°-10°= 50°
m (∡DCB)=m (∡ACB)-m (∡DCB)=60°-20°= 40°
⇒
m (∡BDC)=180° - m (∡DBA)-m (∡DCB)=180° - 50°- 40°= 90°
⇒Δ BDC ESTE TRIUNGHI DREPTUNGHIC
