MathDB

2013.7

Part of Croatia MO (HMO) - geometry

Problems(1)

angle of feet of angle bisectors wanted if <B=120^o

Source: 2013 Croatia MO p7

8/5/2020
In triangle ABCABC, the angle at vertex BB is 120o120^o. Let A1,B1,C1A_1, B_1, C_1 be points on the sides BC,CA,ABBC, CA, AB respectively such that AA1,BB1,CC1AA_1, BB_1, CC_1 are bisectors of the angles of triangle ABCABC. Determine the angle ∠A1B1C1\angle A_1B_1C_1.
geometryanglesangle bisectorAngle Bisectors