Question

Deketahui besar sudut BCA = 25 derajat dan sudut CBO 15 derajat .
=??

Answer 1

Sudut AOB = 50
sudut OAB = 65
sudut ABC = 80
sudut BAC = 75

Answer 2

< AOB = 2 x < BCA
           = 2 x 25⁰
           = 50⁰

segitiga ABO sama kaki, maka: (< OAB = < ABO)
< OAB + < ABO + < AOB = 180⁰
2 ( < OAB ) + < AOB = 180⁰
2 (< OAB ) + 50 = 180⁰
2 ( < OAB ) = 130⁰
< OAB = 65⁰

< ABC = < ABO + < CBO
           = 65⁰ + 15⁰   
           = 80⁰

< BAC = < ABC = 80⁰