Answer:
Adding them together. x = 3/2, y = 8
Step-by-step explanation:
Adding because we want to get rid of a variable. If we add, 2x + 6x = 8x, 1/2 * y + (-1/2 * y) = 0, and 7 + 5 = 12. Adding gets rid of the y variable.
By adding we get that 8x = 12 which gives us x = 12/8 = 3/2
Substituting this back into either equation will give us y = 8.
X^4 - 5x^2 - 36 = 0
(x^2 - 9)(x^2 + 4) = 0
(x-3)(x+3)(x-2)(x+2) = 0
x = -3, -2, 2, 3
You need this key result: in any polygon, the sum of the interior angles is

where
is the number of sides of the polygon.
Your polygon has seven sides, and the measures of all angles are given. So, we can write

Again, we've simply written that the sum of all interior angles is the number of sides, minus two, times 180.
We can simplify both sides: we sum like terms on the left hand side, and we easily compute the right hand side:

and we can solve this equation for
by dividing both sides by 30:

Finally, the required angles is 
Answer:
This is pythagoras
A squared plus b squared equals c squared.
The unknown side is c as its the hypotenuse,
So the length of the first side is 6.4 this squared = 40.96
The other length is 12 as 6 is the radius so the diameter of the circle amd therfore the length of the triangle is 12.
12 squared is 144
144 + 40.96 = 184.96
The length of c squared is 184.96
To find the length of c alone we calculate the square root.
The square root of 184.96 = 13.6
? = 13.6