Area=(Theta/2) * r^2 This should be it, obviously Theta is your angle and you should use radiants in theory.
Answer: equation
Reasoning: So an easy way to remember this is, an equation has an equals sign. So remember equal sounds like equation so that’s a way to know. And an expression doesn’t have an equals sign.
1) 2m - 16 = 2m + 4
2m - 2m = 4 + 16
0 = 20 (no solution)
2) -4(r + 2) = 4(2 - 2r)
-(r + 2) = 2 - 2r
-r - 2 = 2 - 2r
-r + 2r = 2 + 2
r = 4
3) 12(5 + 2y) = 4y - (6 - 9y)
60 + 24y = 4y - 6 + 9y
60 + 24y = 13y - 6
24y - 13y = -6 - 60
11y = -66
y = -6
Set the two values equal to each other with 18x-2=12x+2 and then plug it in to the equation and solve