Answer:
1.28 or 912/715
Step-by-step explanation:
sine= opposite side/hypotenuse
cos=adjacent/ hypotenuse
sine a= 12/13 using the Pythagorean Theorem and solve for the missing side. (which is the adjacent side)
cos a = 5/13
Do the same for sine b
cos b= 9.8/11
add both the cosine value
(5/13)+(9.8/11)=1.28 or 912/715 in fraction form