Answer:
Perpendicular bisectors.
Step-by-step explanation:
This is called a circumscribed circle.
First you construct the perpendicular bisector of one side, then repeat with a second side. Where these lines cross is the center of the circle.
Answer:

Step-by-step explanation:
If a line is perpendicular to a line that has slope m, then the slope of the line is -1 / m.
in this case,
∴
by comparing with 
the slope of the perpendicular line is

use the point-slope form: 
the equation of the perpendicular line is

Answer:
the answer is 29.61
Step-by-step explanation:
cross multiply or set up a basic multiplication box removing the decimals and adding it back
Answer:
i=-12
Step-by-step explanation:
1.) Add 10 to -82 to get the equation 6i=-72
2.) Divide -72 by 6 to get the answer i=-12
Check the picture below.
so, as I see it, we can simply move from the point P, 360° counter-clockwise, the green one, and we'll be landing on a positive angle on the 1st Quadrant, the angle of 360° + 30° = 390°.
we can also move 360° clockwise, the red one, from P, so we'll be landing at -360° + 30 = -330°, also on the 1st Quadrant, but a negative counterpart.
now, if we move by jumps of 360° on either direction, we'll be landing coterminal with P all the time, so if we use simply multiply 360° by "n", some integer, then that angle added or subtracted from 30°, will be coterminal with P.
( 6 , 30°±360n°) where n ∈ ℤ.