![d= √( (x_2 - x_1)^2 + (y_2 - y_1)^2 )](https://img.qammunity.org/2021/formulas/mathematics/middle-school/mgzo7ssu8r7xnts1n2fsbdw2utv815kgrz.png)
![d^2= (x_2 - x_1)^2 + (y_2 - y_1)^2 }](https://img.qammunity.org/2021/formulas/mathematics/middle-school/hlvu0yzhioy4s6413juiusuvdjwj6h7u2g.png)
![d^2 - (x_2 - x_1)^2 = (y_2 - y_1)^2 }](https://img.qammunity.org/2021/formulas/mathematics/middle-school/c2j7t4qmd1lz6862peond7euawyowokbou.png)
![|y_2 - y_1| = √( d^2 - (x_2 - x_1)^2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/zwd1kl60mmcmkxqs3e90ca4vcbiaat4t5s.png)
Let's assume y₂ ≥ y₁. This is wrong; we shouldn't assume that; the question writers did this problem incorrectly. But we'll continue to get the answer they want you to choose.
![y_2 - y_1 = √( d^2 - (x_2 - x_1)^2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/5cjo92s4pjfg1hr08cc0toamvwubzfh1oy.png)
![y_2 = y_1 + √( d^2 - (x_2 - x_1)^2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/zyc4kbmhagu8lr2gg9s3cqgv4q1ap4ek6r.png)
Answer: A
The real answer is none-of-the-above. It's bad when the teachers who write these questions don't really know what they're doing.
The correct answer is y₂ is ambiguous:
![y_2 = y_1 \pm √( d^2 - (x_2 - x_1)^2)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/tn44z8xgpuiwffjsy0nm4wco2xgwqkzjrg.png)