What geometry theorem (corollary, really) is dynamically being illustrated below?[br](Feel free to move the triangle's vertices anywhere you'd like!)
[b]Theorem: [/b][br][br]The acute angles of a right triangle are complementary. [br](Note how this theorem is an immediate result of the [url=https://www.geogebra.org/m/FAhtKpR5]Triangle-Angle-Sum-Theorem[/url]).