&quot;90 degrees&quot; is not confusing to me in the same way that measurements in feet and miles is not confusing. I was raised in a system that emphasized degrees, feet, and miles (USA). But in engineering, metric is the standard&#x2F;default system of measurement. And in software libraries (e.g. JavaScript&#x27;s Math built-in lib) or many calculators, the default is radians, not degrees. So even though degrees is more natural for me, it was worthwhile to get a deeper understanding of radians. The Tau Manifesto got me there. (90 degrees is 1&#x2F;4 turn around a circle, which happens to be expressed as 1&#x2F;4*tau -- and I didn&#x27;t even have to look that up!)