Answer:

Step-by-step explanation:
From figure,

In triangle 

![\Rightarrow (a+b)^2=(a-b)^2+(O' D)^2\\\Rightarrow a^2+b^2+2ab-a^2-b^2+2ab=(O' D)^2\\\Rightarrow 4ab=(O' D)^2\\\Rightarrow O'D=2\sqrt{ab} \\\Rightarrow O' D=2\sqrt{ab}=AB \quad \quad [\because O' DAB\;\; \text{is a rectangle.}]](https://tex.z-dn.net/?f=%5CRightarrow%20%28a%2Bb%29%5E2%3D%28a-b%29%5E2%2B%28O%27%20D%29%5E2%5C%5C%5CRightarrow%20a%5E2%2Bb%5E2%2B2ab-a%5E2-b%5E2%2B2ab%3D%28O%27%20D%29%5E2%5C%5C%5CRightarrow%204ab%3D%28O%27%20D%29%5E2%5C%5C%5CRightarrow%20O%27D%3D2%5Csqrt%7Bab%7D%20%5C%5C%5CRightarrow%20O%27%20D%3D2%5Csqrt%7Bab%7D%3DAB%20%5Cquad%20%5Cquad%20%5B%5Cbecause%20O%27%20DAB%5C%3B%5C%3B%20%5Ctext%7Bis%20a%20rectangle.%7D%5D)
Hence, 
The midpoint formula is:
(point1 + point2)/2
1) (-2 + 12)/2 = 5
2) (-1 +5)/2 = 2
(0+2)/2 = 1
(2,1)
3) Sqrt of (x2-x1)^2 + (y2 - y1)^2
sqrt of (7 -1)^2 + (-7 - 1)^2
sqrt of (6)^2 + (-8)^2
sqrt of 36 + 64
sqrt of 100
10
Hope this helps!
Answer: X = 42
Steps:
(3x + 12) + x = 180
3x + 12 + x = 180
4x + 12 = 180
4x = 180 - 12
4x = 168
x = 168/4
x = 42
Check:
(3x + 12) + x = 180
3x + 12 + x = 180
3(42) + 12 + 42 = 180
126 + 12 + 42 = 180
180 = 180 ✅
I would appreciate the brainliest if this was correct and had helpful & clear steps! :)
Answer:
The dimensions of the border are 7 yd by 6.25 yd.