Answer:
Step-by-step explanation:

Then using trygonometric table or a graph we read that:

Period of cosinus function = 2π
So the last answer is
Answer:
b = 12
Step-by-step explanation:
7b = 84
We can break down 7b as 7 x b
7 x b = 84
We divide both sides by 7:
7 x b ÷ 7 = 84 ÷ 7
b = 12
-Chetan K
Just move all terms to the left side and set equal to zero. Then, set each factor equal to zero.
a = 5,1