Jawabanmu

2014-06-02T02:09:29+07:00
A^2=b^2+c^2-2bc cos A
(akr 13)^2 = 3^2 + 4^2 - 2.3.4 cos A
13 = 9 + 16 - 24 cos A
24 cos A = 25 - 13
24 cos A = 12
cos A = 1/2
sdt A = 45 derajat