Answer:

Step-by-step explanation:
Notice that you are given an isosceles right-angle triangle to solve, since each of its two acute angles measures
. Then such means that the sides opposite to these acute angles (the so called "legs" of this right angle triangle) must also be of the same length (x).
We can then use the Pythagorean theorem that relates the square of the hypotenuse to the addition of the squares of the triangles legs:

We use just the positive root, since we are looking for an actual length. then, the requested side is:

Quadrilateral. If you add the angles up on any quadrilateral, it equals 360 (it should always add to 360 for a quadrilateral)
Answer:
(1,2)
Step-by-step explanation:
x+4y = 9
2x -4y= -6
Add the equations together
x+4y = 9
2x -4y= -6
-------------------
3x +0y = 3
3x=3
Divide by 3
3x/3 = 3/3
x=1
Now find y
x+4y = 9
1 +4y =9
Subtract 1 from each side
4y = 8
Divide by 4
4y/4 = 8/4
y =2