53: 800 and 900
54: 700 and 800
55: 500 and 600
56: 2,771,100 and 2,771,200
57: 90,120,000 and 90,120,100
58: 631,900 and 632,000
59: 93,300 and 93,400
60: 200 and 300
61: 900 and 1000
62: 39,576,700 and 39,576,800
63: 24,900 and 25,000
64: 471,100 and 471,200
You need to add a picture in order for others to understand what you are referring to.
Since
and
, we can rewrite the right side of the equation as

Using the identity
, we can subtract
from either side to obtain the identity 
substituting that into our previous expression, the right side of our equation simply becomes

We can now write our whole equation as

Adding 2 to both sides:

dividing both sides by 3:


When 0 ≤ x ≤ π, tan x can only be equal to 1 when sin x = cos x, which happens at x = π/4, and it can only be equal to -1 when -sin x = cos x, which happens at x = 3π/4
The answer to that question is C