For future viewers, there's the cosine rule for non-right-angle triangles. And if you aren't allowed to use a calculator, there's also standard trig identities for equilateral and right angle triangles (i.e. the angles will always be the same, and some ratio of sides). E.g. sin(60°) = 2/√3.
Hey, Andy. I have an idea about, you can try design your RU-vid banner with math and leave some track like a line or curve in it, so people know you like doing that. Idk, it's just an idea. Maybe design it normallly will be easier.
Did I overcomplicate this by using the Heron formula from the last video on this channel that I watched? Yes. Did I realize then then the simpler way shown here actually became important later on? Yes. Welp. This is why I watch. This channel is a fun way to learn, and specifically to learn from your mistakes.