Question

For positive acute angles
�
A and
�
,
B, it is known that
cos
⁡
�
=
11
61
cosA=
61
11
​
and
sin
⁡
�
=
3
5
.
sinB=
5
3
​
. Find the value of
cos
⁡
(
�
+
�
)
cos(A+B) in simplest form.