Question

CosA=3/5 ,CosB=5/13 then what is the value of Cos(A-B)​

Answer 1

Answer:

63/65

Step-by-step explanation:

given, cosA=3/5, cosB=5/13 sinA=[1- (3/5)^2]^1/2 =(16/25)^1/2 =4/5 sinB=[1-(5/13)^2]^1/2 =(144/169) ^1/2 =12/13 now, cos(A-B)= cosA.cosB+sinA.sinB =3/5×5/13 +4/5×12/13 =3/13 +48/65 =15+48/65 =63/65