How do I use quod erat demonstrandum in a sentence?

You can use "quod erat demonstrandum" (often abbreviated as Q.E.D.) in a sentence to signify that you have successfully proven a point or completed a mathematical proof.

Here are some examples:

* "Therefore, the sum of the angles in a triangle always equals 180 degrees. Q.E.D."

* "By analyzing the data, we can conclude that the company's growth strategy is effective. Q.E.D."

* "The evidence clearly shows that the defendant was not at the scene of the crime. Q.E.D."

However, "Q.E.D." is a bit outdated and is rarely used in modern writing, especially in casual settings. It's generally considered more appropriate for formal mathematical or scientific papers.

Instead of "Q.E.D.", you can use other phrases like:

* "This proves that..."

* "Therefore, we can conclude that..."

* "As shown above,..."

* "This completes the proof."

Ultimately, the best way to use "Q.E.D." or any other ending phrase is to choose one that fits the tone and context of your writing.