4,3 x is the first number then y
Not sure why such an old question is showing up on my feed...
Anyway, let

and

. Then we want to find the exact value of

.
Use the angle difference identity:

and right away we find

. By the Pythagorean theorem, we also find

. (Actually, this could potentially be negative, but let's assume all angles are in the first quadrant for convenience.)
Meanwhile, if

, then (by Pythagorean theorem)

, so

. And from this,

.
So,
Answer:
6x + 7
6 * 2
12 + 7
=19
Step-by-step explanation:
3,857:
1. 3 is located in the thousands place
2. Since 8 is bigger than 3, it's telling it to go up a number (turning 3 into a 4)
Stays the Same: 1,2,3,4
Goes Up: 5,6,7,8, etc.
So 3,857 is now rounded into 4,000