Answer:
i)
Step-by-step explanation:
Tan a = 1
Tan A = tan 45
A = 45.
Now,
Tan b = root 3
Tan b = tan 60.
B = 60.
Now ,
Cos a * cos b - sin A * sin B
= cos 45 * cos 60 - sin 45 * sin 60
= 1/root 2 * 1/2 - 1/root 2 * root 3 /2
= 1 /root 2 ( 1/2 - root 3 /2)
= 1/root 2 * 1 - root 3 /2
= 1 - root 3 / 2 root 2.
