In ΔABC above, BC is produced to D, /AB/ = /AC/ and ∠BAC = 50o. Find ∠ACD
Attached Figure / Diagram
A
50o
B
60o
C
65o
D
100o
E
115o
Verified Correct Answer: E.
Step-by-Step Mathematical Solution
ACB = ABC [Base angles of isoceles triangle]
ACB + ABC + 50o = 180o[sum of angles in a triangle]
ACB + ABC = 180o - 50o = 130o
ACB 130o/2 = 65o
ACD + ACB = 180o[sum of ∠s on a straight line]
ACD + 65o = 180o
ACD = 180o - 65o = 115o
Source: Myschool Past Questions Archive (Record #23782)